Underwater detection apparatus and underwater detection method

ABSTRACT

An underwater detection apparatus is provided which includes a transmission transducer, a reception transducer, and a motor. The transmission transducer transmits a transmission wave within a given fan-shaped transmission space, the fan-shaped transmission space having a first transmission width in a given first plane and a second transmission width in a second plane perpendicular to the first plane. The reception transducer receives, as a reception wave, a reflection wave of the transmission wave within a given fan-shaped reception space, the fan-shaped reception space having a first reception width in the first plane and a second reception width in the second plane, the second reception width being wider than the second transmission width, and in the second plane, the fan-shaped transmission space being within the fan-shaped reception space. The motor rotates the fan-shaped transmission space and the fan-shaped reception space.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The application claims priority under 35 U.S.C. § 119 to Japanese PatentApplication No. 2019-095204, which was filed on May 21 2019, the entiredisclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an underwater detection apparatus andan underwater detection method which detect underwater.

BACKGROUND

As disclosed in U.S. Pat. No. 9,335,412B2, it is known that anunderwater detection apparatus transmits a fan beam from a transmissionelement and receives an echo by a reception element.

The underwater detection apparatus disclosed in U.S. Pat. No.9,335,412B2 performs a transmission and reception processings of a pulsetype while rotating a wave transmission element and a wave receivingelement by a motor. A reception fan beam is completely included in arange of a transmission fan beam in a plan view.

Meanwhile, an underwater detection apparatus utilizing a so-calledmulti-ping type is known. Also in this multi-ping type, a reception fanbeam may be formed, while transmitting a transmission fan beam byrotating a transmission element and a reception element about a verticalaxis by the motor. In such a configuration, it is necessary to increasea transmission horizontal beam width in the rotating direction as anapparatus scanning direction, in order to accelerate an image updatecycle at which a detection result is displayed on a screen. Byincreasing the transmission horizontal beam width, a reflection waveincluded in a reception beam is quickly detectable, and, as a result,the image update cycle can be accelerated.

Here, it is known to utilize the narrow transmission and reception beamsso that underwater is detectable with appropriate resolution. However,since underwater sound speed is slow, the echo will be overlooked if thetransmission and reception beams are moved (e.g., the transmission andreception beams are rotated by a PPI sonar). As a measure for reducingsuch an overlook of the echo, it is possible to widen the transmissionbeam, while keeping the reception beam narrow, for example, in theconfiguration of U.S. Pat. No. 9,335,412B2. With this configuration,even if the transmission and reception beams are rotated, theappropriate resolution is securable and the overlook of the echo isreduced.

However, since the widening of the transmission beam width induces areduction in the source level, and as a result, induces a reduction inthe detection range, it is desirable not to expand the transmission beamwidth as much as possible.

SUMMARY

The present disclosure is to solve the above situations, and one purposethereof is to provide an underwater detection apparatus and anunderwater detection method, capable of both speeding-up of an updatingcycle of a detection result image and preventing a reduction in adetection range.

According to one aspect of the present disclosure, an underwaterdetection apparatus is provided which includes a transmissiontransducer, a reception transducer, and a motor. The transmissiontransducer transmits a transmission wave within a given fan-shapedtransmission space, the fan-shaped transmission space having a firsttransmission width in a given first plane and a second transmissionwidth in a second plane perpendicular to the first plane. The receptiontransducer receives, as a reception wave, a reflection wave of thetransmission wave within a given fan-shaped reception space, thefan-shaped reception space having a first reception width in the firstplane and a second reception width in the second plane, the secondreception width being wider than the second transmission width, and inthe second plane, the fan-shaped transmission space being within thefan-shaped reception space. The motor rotates the fan-shapedtransmission space and the fan-shaped reception space.

According to some example embodiments, when the motor rotates in a givendirection, one edge of a pair of edges of the fan-shaped transmissionspace may be positioned on a front edge of the fan-shaped receptionspace relative to the given direction.

According to another aspect of the present disclosure, an underwaterdetection method is provided, which includes transmitting a transmissionwave within a given fan-shaped transmission space, the fan-shapedtransmission space having a first transmission width in a given firstplane and a second transmission width in a second plane perpendicular tothe first plane, receiving, as a reception wave, a reflection wave ofthe transmission wave within a given fan-shaped reception space, thefan-shaped reception space having a first reception width in the firstplane and a second reception width in the second plane, the secondreception width being wider than the second transmission width, and inthe second plane, the fan-shaped transmission space being within thefan-shaped reception space, and rotating the fan-shaped transmissionspace and the fan-shaped reception space.

According to the present disclosure, both the speed-up of the updatingcycle of the detection result image and the prevention of the reductionin the detection range can be achieved.

BRIEF DESCRIPTION OF DRAWINGS

The present disclosure is illustrated by way of example and not by wayof limitation in the figures of the accompanying drawings, in which likereference numerals indicate like elements and in which:

FIG. 1 is a block diagram illustrating a configuration of an underwaterdetection apparatus according to one embodiment of the presentdisclosure;

FIG. 2 is a perspective view schematically illustrating a substantialpart of a wave transceiving unit;

FIG. 3 is a view schematically illustrating a transmission beam formedby a wave transmitter and a reception beam received by a wave receiver;

FIG. 4A is a plan view of a ship to which the underwater detectionapparatus is mounted, seen in a direction perpendicular to a secondplane, and schematically illustrates a transmission fan-shaped spaceformed by the wave transmitter and a reception fan-shaped space receivedby the wave receiver;

FIG. 4B is a view illustrating a modification of a relation between thetransmission fan-shaped space and the reception fan-shaped space in thesecond plane;

FIG. 4C is a view illustrating a further modification of the relationbetween the transmission fan-shaped space and the reception fan-shapedspace in the second plane;

FIG. 5 is a block diagram illustrating a configuration of a signalprocessor;

FIG. 6 is a plan view schematically illustrating a substantial part of afirst modification of the first embodiment;

FIG. 7 is a flowchart illustrating one example of processing in thefirst modification of the first embodiment illustrated in FIG. 6;

FIG. 8 is a plan view schematically illustrating a substantial part of asecond modification of the first embodiment;

FIG. 9 is a flowchart illustrating one example of processing in thesecond modification of the first embodiment illustrated in FIG. 8;

FIG. 10 is a block diagram illustrating a configuration of an underwaterdetection apparatus according to a second embodiment of the presentdisclosure;

FIGS. 11A and 11B are plan views of the ship to which the underwaterdetection apparatus is mounted, seen in a direction perpendicular to thesecond plane perpendicular to a first plane, and schematicallyillustrate a transmission fan-shaped space and a reception fan-shapedspace, where FIG. 11A illustrates a state where the wave transmitter andthe wave receiver are rotated in a first direction, and FIG. 11Billustrates a state where the wave transmitter and the wave receiver arerotated in a second direction;

FIG. 12 is a flowchart illustrating one example of processing in thesecond embodiment;

FIG. 13 is a side view schematically illustrating a substantial part ofa second modification of the second embodiment, where a part isillustrated in a cross-section;

FIG. 14 is a block diagram illustrating a configuration of an underwaterdetection apparatus according to a third embodiment of the presentdisclosure;

FIG. 15 is a view schematically illustrating a transmission beam formedby the wave transmitter and a reception beam received by the wavereceiver;

FIG. 16 is a plan view of the ship to which the underwater detectionapparatus is mounted, seen in a direction perpendicular to the secondplane, where a transmission fan-shaped space formed by the wavetransmitter and a reception fan-shaped space received by the wavereceiver are schematically illustrated;

FIG. 17 is a block diagram illustrating a configuration of an underwaterdetection apparatus according to a modification of the third embodimentof the present disclosure;

FIG. 18 is a view schematically illustrating a transmission beam formedby the wave transmitter and a second wave transmitter, and a receptionbeam received by the wave receiver;

FIG. 19 is a plan view of the ship to which the underwater detectionapparatus is mounted, seen in a direction perpendicular to the secondplane, where a transmission fan-shaped space formed by the wavetransmitter and a reception fan-shaped space are schematicallyillustrated;

FIG. 20 is a view schematically illustrating a substantial part of afurther modification of a substantial part of a transducer; and

FIG. 21 is a view schematically illustrating an underwater detectionapparatus according to a fourth embodiment of the present disclosure.

DETAILED DESCRIPTION First Embodiment

Hereinafter, an underwater detection apparatus according to a firstembodiment of the present disclosure is described with reference to theaccompanying drawings. An underwater detection apparatus 1 according tothis embodiment of the present disclosure may be an ultrasonic detectionapparatus of a so-called “multi-ping” type. This multi-ping type mayalso be referred to as a “multi-pulse” type.

General pulse-type underwater detection apparatuses among all the pulsetypes other than the multi-ping type may transmit a transmission pulsewave (transmission wave), a wave receiver of the underwater detectionapparatus may then receive a reflection wave of the transmission pulsewave as a reception wave while the transmission pulse wave goes andcomes back in a detection range. Then, after a time for the transmissionpulse wave to go and come back in the detection range is lapsed, thesubsequent transmission pulse wave may be transmitted. On the otherhand, the underwater detection apparatus of the multi-ping type amongall the pulse types may first transmit a transmission pulse wave in agiven frequency band, and transmit the subsequent transmission pulsewave in a frequency band different from the given frequency band beforethe transmission pulse wave goes and comes back in the detection range.The reflection wave of the transmission pulse wave may be extracted by afilter corresponding to each frequency band. Therefore, according to theunderwater detection apparatus of the multi-ping type, since a wavetransmission interval of the transmission pulse wave can be narrowed, adetection cycle of a target object can be accelerated compared with theunderwater detection apparatus of the general pulse type.

Note that, in this embodiment, one example in which the underwaterdetection apparatus 1 is the multi-ping type is described, however, theconfiguration may be altered. For example, the present disclosure may beapplied to the underwater detection apparatus which performstransmission and reception processing of the general pulse type otherthan the multi-ping type, or may be applied to the underwater detectionapparatus which performs transmission and reception processing of a FMCW(Frequency Modulated Continuous Wave) type.

For example, the underwater detection apparatus 1 is mounted to thebottom of a ship S (hereinafter, referred to as “the ship” todistinguish from other ships), and it may be mainly used for detectionof a target object, such as a single fish and a school of fish. Inaddition, the underwater detection apparatus 1 may be used for detectionof ups and downs of the seabed like a reef, a structure like anartificial fish reef, etc. Moreover, according to this underwaterdetection apparatus 1, a three-dimensional position and shape of thetarget object can be grasped, as will be described later in detail. Notethat the present disclosure may be applied to ships which typicallytravel on water or sea which are referred to as surface ships, and mayalso be applied to other types of ships including boats, dinghies,watercrafts, and vessels. Further, the present disclosure may also beapplied, if applicable, to submarines.

[Entire Configuration]

FIG. 1 is a block diagram illustrating a configuration of the underwaterdetection apparatus 1 according to this embodiment of the presentdisclosure. As illustrated in FIG. 1, the underwater detection apparatus1 may include a transceiving device 2, a signal processor 3 (which mayalso be referred to as processing circuitry 3), and a display unit 4.

[Configuration of Transceiving Device]

The transceiving device 2 may include a wave transceiving unit 5 and atransceiving part 6.

The wave transceiving unit 5 may include a wave transmitter 11constituted as a transmission transducer, a wave receiver 13 constitutedas a reception transducer, a bracket 15 which supports the wavetransmitter 11 and the wave receiver 13, a motor 16 as a rotary drivingpart, and a rotational angle detecting part 18.

FIG. 2 is a perspective view schematically illustrating a substantialpart of the wave transceiving unit 5. FIG. 3 is a view schematicallyillustrating a transmission beam TB formed by the wave transmitter 11,and a reception beam RB received by the wave receiver 13. Referring toFIGS. 1 to 3, the wave transmitter 11 may be provided in order totransmit a pulse-shaped ultrasonic wave underwater. The wave transmitter11 may have a wave transmitting surface 11 b. This wave transmittingsurface 11 b may be a surface from which the ultrasonic wave istransmitted, and the wave transmitter 11 may be installed in the bottomof the ship S so that the wave transmitting surface 11 b is disposedunder the sea surface, and may be accommodated in a casing (notillustrated). The wave transmitter 11 may have a configuration in whichone or more wave transmission elements 11 a as an ultrasonic transduceris attached to a casing 11 c. In this embodiment, a plurality of wavetransmission elements 11 a may be disposed linearly. That is, the wavetransmitter 11 may be a linear array.

The wave receiver 13 may have a configuration in which one or more wavereceiving elements 13 a as an ultrasonic transducer is attached to acasing 13 c. The wave receiver 13 may be provided separately from thewave transmitter 11. The wave receiver 13 may have a wave receivingsurface 13 b. The wave receiving surface 13 b may be a surface forreceiving the ultrasonic wave, and the wave receiver 13 may be installedin the bottom of the ship S so that the wave receiving surface 13 b isdisposed under the sea surface, and may be accommodated in the casing(not illustrated) together with the wave transmitter 11. Each wavereceiving element 13 a of the wave receiver 13 may receive, as thereception wave, the reflection wave of each transmission pulse wave(each transmission wave) which is the ultrasonic wave transmitted fromthe wave transmitter 11, and convert it into an echo signal as anelectric signal. In this embodiment, a plurality of wave receivingelements 13 a may be disposed linearly. That is, the wave receiver 13may be a linear array.

In this embodiment, the wave transmitter 11 and the wave receiver 13 maybe separate components, and therefore, they may be mutually differenttransducers. In this embodiment, a length of the wave transmissionelement 11 a of the wave transmitter 11 (i.e., a lateral width) may beset longer than a length of the wave receiving element 13 a of the wavereceiver 13 (i.e., a lateral width). The wave transmitter 11 and thewave receiver 13 may be supported by the bracket 15 as described above.For example, the bracket 15 may be a frame member formed by combiningsteel members, and may be coupled to the casing 11 c of the wavetransmitter 11 and to the casing 13 c of the wave receiver 13.

The wave transmitter 11 may be fixed at a given angle position about agiven vertical axis 11 d with respect to the wave receiver 13. Thevertical axis 11 d may be an axis which extends in the longitudinaldirection of the casing 11 c (i.e., the array direction of the pluralityof wave transmission elements 11 a) and penetrates the center of anupper surface and a lower surface of the casing 11 c. By setting theangle of the wave transmitter 11 about the vertical axis 11 d, arelative position of a transmission fan-shaped space T1 and a receptionfan-shaped space R1, which will be described later, can be set.

Moreover, the wave receiver 13 may be fixed to a given angle positionabout a second given horizontal axis 13 e with respect to the wavetransmitter 11. The second horizontal axis 13 e may be an axis whichextends in the transverse direction of the casing 13 c (i.e., a widthdirection of the wave receiving element 13 a) and penetrates the centerof both left and right side surfaces of the casing 13 c. By setting theangle of the wave receiver 13 about the second horizontal axis 13 e, adirection of the reception fan-shaped space R1 with respect to theseabed surface can be set optimally.

Moreover, the wave transmitter 11 may be fixed to a given angle positionabout a given first horizontal axis 11 e with respect to the wavereceiver 13. The first horizontal axis 11 e may be an axis which extendsin the transverse direction of the casing 11 c, i.e., in the widthdirection of the wave transmission element 11 a, and penetrates thecenter of both left and right side surfaces of the casing 11 c. Bysetting the angle of the wave transmitter 11 about the first horizontalaxis 11 e, a direction of the transmission fan-shaped space T1 withrespect to the seabed surface can be set optimally.

A vertical plane which spreads in the vertical direction and includesthe first horizontal axis 11 e and a vertical plane which spreads in thevertical direction and includes the second horizontal axis 13 e may bedifferent from each other. That is, the vertical plane including thefirst horizontal axis 11 e and the vertical plane including the secondhorizontal axis 13 e may be constituted as mutually different verticalplanes, and the first horizontal axis 11 e and the second horizontalaxis 13 e may be constituted so as not to be included in a commonvertical plane.

As described above, the underwater detection apparatus 1 may rotate thewave transmitter 11 with respect to the first horizontal axis 11 e todispose the wave transmitting surface 11 b of the wave transmitter 11obliquely to the vertical plane. Moreover, the underwater detectionapparatus 1 may rotate the wave receiver 13 with respect to the secondhorizontal axis 13 e to dispose the wave receiving surface 13 b of thewave receiver 13 obliquely to the vertical plane. The first horizontalaxis 11 e and the second horizontal axis 13 e may not be included in thecommon vertical plane. Therefore, in the underwater detection apparatus1, the wave transmitting surface 11 b and the wave receiving surface 13b may be both disposed obliquely to the vertical plane, and a directionperpendicular to the wave transmitting surface 11 b and a directionperpendicular to the wave receiving surface 13 b may not be parallel toeach other, but mutually different directions. The wave transmitter 11and the wave receiver 13 may be integrally rotated by the motor 16.

In this embodiment, the motor 16 may drive the wave transmitter 11 andthe wave receiver 13 to rotate them with the bracket 15 about a rotationaxis L1 which is the center axis extending in the vertical direction.The motor 16 may be a motor of which the rotational position iscontrollable, such as a stepping motor, a servo motor, etc. The motor 16may be driven in response to an operational instruction from the signalprocessor 3, by drive current according to this operational instruction.An output shaft 16 a of the motor 16 may be coupled to the bracket 15 sothat power transfer is possible, and the wave transmitter 11 and thewave receiver 13 may rotate along a horizontal plane perpendicular tothe vertical direction. In this embodiment, a rotating direction of themotor 16 may be a given fixed direction, and may be a first direction K1which is one of the rotating directions about the rotation axis L1. Inthis embodiment, a slip ring may be used so that a twist does not occuron cables connected to the motor 16 due to the fixation of the rotatingdirection of the motor 16. In this embodiment, the motor 16 maycontinuously rotate the wave transmitter 11 and the wave receiver 13.However, without being limited to this configuration, the motor 16 mayrepeat a rotation and a stop or a suspension so that it repeats anoperation in which it rotates by a given angle at every given timeinterval and suspends for a given period of time after the rotation.

The rotating speed of the motor 16 when the underwater detection isperformed may be set as the normal rotating speed. The normal rotatingspeed in this case may mean a rotating speed required for transmittingand receiving the echo using the multi-pin technology. For example, therotating speed (angle/time) may be set to below “wave receivinghorizontal beam width”/“round-trip propagation time of sound wave in arange where the reception wave detection is to be carried out/speed-uprate.”

The rotational angle detecting part 18 may be attached to the motor 16.Note that the rotational angle detecting part 18 may be attached to themotor 16, or may be disposed separately from the motor 16. For example,an encoder is used as the rotational angle detecting part 18. However,without being limited to this configuration, the signal for controllingthe rotation of the motor 16 may be analyzed and converted into angularinformation. In detail, if the stepping motor is used as the motor 16,the number of instruction pulses inputted into the stepping motor may becounted and converted into the angular information. In the underwaterdetection apparatus 1, the angle position of the wave transmitter 11 andthe wave receiver 13 in (p-direction may be calculated based on therotational angle of the motor 16 detected by the rotational angledetecting part 18. Note that the (p-direction may be a direction aboutthe rotation axis L1 of the motor 16.

The wave transmitter 11 may form the transmission fan-shaped space T1which is a range or space to which the three-dimensional transmissionbeam TB is outputted as illustrated in FIG. 3. The transmissionfan-shaped space T1 may be a substantially fan-shaped beam (fan beam).That is, the wave transmitter 11 may transmit the transmission wave intothe transmission fan-shaped space T1. The transmission fan-shaped spaceT1 may be a range or space which includes a center axis Tx at whichtransmission signal power of the transmission wave transmitted from thewave transmitter 11 becomes the maximum, and where the transmissionsignal power is halved to −3 dB from the maximum. That is, thetransmission fan-shaped space T1 may be a range or space having thepower at or more than half of the maximum power of the transmission wavetransmitted from the wave transmitter 11. In this embodiment, the wavetransmitter 11 may be provided to the ship's bottom so that the centeraxis Tx of the transmission fan-shaped space T1 becomes obliquely to thevertical direction (z-axis direction in FIG. 3). Note that thetransmission fan-shaped space T1 may be a range where the transmissionsignal power is reduced by −n1 dB (n1 is set according to a detectiontarget object etc. of the underwater detection apparatus 1) from themaximum.

The transmission fan-shaped space T1 may have a first transmitting widthTiO in a given first plane P1, and have a second transmitting width Tθ2in a second plane P2 perpendicular to the first plane P1. The firsttransmitting width Tθ1 may be wider than the second transmitting widthTθ2. The transmission fan-shaped space T1 may be formed in the fan shapein both the first plane P1 and the second plane P2. In this embodiment,the first plane P1 may be a vertical plane including the rotation axisL1 of the motor 16. Moreover, in this embodiment, the second plane P2may be a horizontal plane. The first transmitting width Tθ1 may be anangle width about the horizontal axis centering on the wave transmitter11. The second transmitting width Tθ2 may be an angle width about therotation axis L1 of the motor 16.

Note that, as described above, when the transmission signal power atedges Te1 and Te2 of the transmission fan-shaped space T1 is a magnitudewhich is −3 dB that from the transmission signal power at the centeraxis Tx, the second transmitting width Tθ2 is smaller than the firsttransmitting width Tθ1. On the other hand, for example, when thetransmission signal power at the edges Te1 and Te2 of the transmissionfan-shaped space T1 is a magnitude which is −10 dB (i.e., smaller than−3 dB) that from the transmission signal power at the center axis Tx,the second transmitting width Tθ2 may be larger than the firsttransmitting width Tθ1.

An angle formed by a direction which is perpendicular to the wavetransmitting surface 11 b of the linear array and in which thetransmission fan-shaped space T1 is formed, and the horizontal plane,may be any angle as long as it is within a range from 0° which is anangle in case where the linear array is disposed in the verticaldirection to 90° which is an angle in case where the linear array isdisposed in the horizontal direction.

The wave receiver 13 may receive a signal of the reception fan-shapedspace R1 where the three-dimensional reception beam RB is formed asillustrated in FIG. 3. The reception fan-shaped space R1 may be asubstantially fan-shaped beam. That is, the wave receiver 13 may receivethe reception wave which is the reflection wave of the transmission wavewithin the reception fan-shaped space R1. The reception fan-shaped spaceR1 may be a range or space which includes a center axis Rx at whichreception power sensitivity of the wave receiver 13 becomes the maximum,and where the reception power sensitivity of the wave receiver 13 ishalved from the maximum to −3 dB. That is, the reception fan-shapedspace R1 may be a range or space having the sensitivity at or more thanhalf of the maximum reception power sensitivity of the wave receiver 13.In this embodiment, the wave receiver 13 may be provided to the ship'sbottom so that the center axis Rx of the reception fan-shaped space R1becomes obliquely to the vertical direction (the z-axis direction inFIG. 3). Note that the reception fan-shaped space R1 may be a rangewhere the reception power sensitivity is reduced from the maximum by −n2dB (n2 is set according to the detection target object etc. of theunderwater detection apparatus 1).

The motor 16 may rotate the transmission fan-shaped space T1 and thereception fan-shaped space R1 about the rotation axis L1 which is theaxis perpendicular to the second plane P2. In detail, the motor 16 mayrotate the transmission fan-shaped space T1 and the reception fan-shapedspace R1 by rotating the wave transmitter 11 and the wave receiver 13.

The wave receiver 13 of this embodiment may perform a detection by thethin reception beam RB which scans electronically inside the receptionfan-shaped space R1 as the fan-shaped space in which the linear array ofthe wave receiver 13 has a gain by performing a beam forming with thetransceiving part 6 and the signal processor 3 which will be describedin detail below.

The reception fan-shaped space R1 may have a first receiving width Rθ1in the first plane P1 and a second receiving width Rθ2 in the secondplane P2, and the first receiving width Rθ1 may be wider than the secondreceiving width Rθ2. Further, the second receiving width Rθ2 of thereception fan-shaped space R1 may be wider than the second transmittingwidth Tθ2 of the transmission fan-shaped space T1 (i.e., Rθ2>Tθ2). Thereception fan-shaped space R1 may be formed in the fan shape both in thefirst plane P1 and the second plane P2. The first receiving width Rθ1may be an angle width about the horizontal axis centering on the wavereceiver 13. The second receiving width Rθ2 may be an angle width aboutthe rotation axis L1 of the motor 16.

Note that, as described above, when the reception power sensitivity atedges Re1 and Re2 of the reception fan-shaped space R1 is the magnitudeof −3 dB from the reception power sensitivity at the center axis Rx, thesecond receiving width Rθ2 is smaller than the first receiving widthRθ1. On the other hand, for example, when the reception powersensitivity at the edges Re1 and Re2 of the reception fan-shaped spaceR1 is the magnitude of −10 dB (i.e., smaller than −3 dB) of thereception power sensitivity at the center axis Rx, the second receivingwidth Rθ2 may be larger than the first receiving width Rθ1.

The first transmitting width Tθ1 and the first receiving width Rθ1 arenot limited in particular, or may be within a range of 6° to 90°. Forexample, although the second receiving width Rθ2 is 36°, it may not belimited to this width or may be an angle less than 90° as long as it islarger than the second transmitting width Tθ2. On the other hand, forexample, the second transmitting width Tθ2 is 6°.

The angle formed by the direction perpendicular to the wave receivingsurface 13 b of the linear array and in which the reception fan-shapedspace R1 is formed, and the horizontal plane, may be any angle, as longas it is within a range from 0° which is the angle in case where thelinear array is disposed in the vertical direction to 90° which is theangle in case where the linear array is disposed in the horizontaldirection.

FIG. 4A is a plan view of the ship S to which the underwater detectionapparatus 1 is mounted, seen in a direction perpendicular to the secondplane P2, and schematically illustrates the transmission fan-shapedspace T1 formed by the wave transmitter 11 and the reception fan-shapedspace R1 received by the wave receiver 13. Note that, in each of FIGS.4A to 4C, although a distance from the ship S to a tip end of thereception fan-shaped space R1 differs from a distance from the ship S toa tip end of the transmission fan-shaped space T1, this difference maybe for the sake of facilitating the illustration and does notnecessarily show the actual ranges accurately. Referring to FIGS. 1 to4A, in the plan view, the transmission fan-shaped space T1 and thereception fan-shaped space R1 may be rotated covering all the directionsaround the ship S by the wave transmitter 11 and the wave receiver 13rotating about the rotation axis L1 in the first direction K1 inconnection with the rotation of the motor 16.

The underwater detection apparatus 1 may calculate rotational angularpositions of the wave transmitter 11 and the wave receiver 13 about therotation axis L1 based on the rotational angle of the motor 16 detectedby the rotational angle detecting part 18.

In the second plane P2, the central line Tx of the transmissionfan-shaped space T1 may be a line at which the transmission signal poweris the highest in the transmission fan-shaped space T1. On the otherhand, the first transmission edge Te1 and the second transmission edgeTe2 as a pair of edges of the transmission fan-shaped space T1 about therotation axis L1 in the second plane P2 may be lines at positions wherethe transmission signal power is the lowest in the transmissionfan-shaped space T1. The transmission signal power at these transmissionedges Te1 and Te2 may be a half of the transmission signal power at thecenter axis Tx. For example, when the motor 16 rotates, in the planview, in the first direction K1 as a clockwise direction, the firsttransmission edge Te1 may be a leading edge or front edge in the firstdirection K1 and the second transmission edge Te2 may be a trailing edgein the first direction K1.

In the second plane P2, the center axis Rx of the reception fan-shapedspace R1 may be a line at which the reception power sensitivity is thehighest in the reception fan-shaped space R1. On the other hand, aboutthe rotation axis L1 in the second plane P2, the first reception edgeRe1 and the second reception edge Re2 as the pair of edges of thereception fan-shaped space R1 may be the lines at the positions wherethe reception power sensitivity is the lowest in the receptionfan-shaped space R1. In this embodiment, the reception power sensitivityin the reception edges Re1 and Re2 may be a half of the reception powersensitivity at the center axis Rx. When the motor 16 rotates in thefirst direction K1, the first reception edge Re1 may be the leading edgein the first direction K1 and the second reception edge Re2 may be thetrailing edge in the first direction K1.

In this embodiment, in the second plane P2, the transmission fan-shapedspace T1 may be located in the reception fan-shaped space R1. That is,the transmission fan-shaped space T1 may be located so as to be includedin the reception fan-shaped space R1.

In detail, in the second plane P2, both the pair of the transmissionedges Te1 and Te2 of the transmission fan-shaped space T1 may be locatedin the reception fan-shaped space R1. In this embodiment, thetransmission fan-shaped space T1 may be located in the receptionfan-shaped space R1 at the angle position near a substantially center inthe range of the angle width of the second receiving width Rθ2. Further,in this embodiment, in the second plane P2, the center axis Tx of thetransmission fan-shaped space T1 and the center axis Rx of the receptionfan-shaped space R1 may not overlap with each other, and the center axisTx of the transmission fan-shaped space T1 may be offset to one side ofthe transmission fan-shaped space T1 in the first direction K1 (in moredetail, forward or front side in the first direction K1) with respect tothe center axis Rx of the reception fan-shaped space R1. Therefore, inthe underwater detection apparatus 1, the wave transmitter 11 and thewave receiver 13 may be configured so that the transmission fan-shapedspace T1 is located forward or front side in the rotating direction ofthe motor 16 (the first direction K1) in the reception fan-shaped spaceR1, when the motor 16 rotates in the first direction K1 (the givendirection). Note that, in this embodiment, although the center axis Txof the transmission fan-shaped space T1 and the center axis Rx of thereception fan-shaped space R1 are not overlapped with each other in thesecond plane P2, this configuration may be altered. That is, in thesecond plane P2, the center axis Tx of the transmission fan-shaped spaceT1 and the center axis Rx of the reception fan-shaped space R1 may beoverlapped with each other.

Note that, in FIG. 4A, although the transmission fan-shaped space T1 islocated in the reception fan-shaped space R1 at the angle position nearthe substantially center in the range of the angle width of the secondreceiving width Rθ2, this configuration may be altered. That is,relations other than the relation between the transmission fan-shapedspace T1 and the reception fan-shaped space R1 which is illustrated inFIG. 4A may be established. One example of such a relation is describedwith reference to FIG. 4B.

FIG. 4B is a view illustrating a modification of the relation betweenthe transmission fan-shaped space T1 and the reception fan-shaped spaceR1 in the second plane P2. In this modification, the transmissionfan-shaped space T1 may be located in the reception fan-shaped space R1,and the center axis Tx of the transmission fan-shaped space T1 maygreatly be offset forward or front side in the first direction K1 withrespect to the center axis Rx of the reception fan-shaped space R1, ascompared with the configuration illustrated in FIG. 4A. Therefore, inthis modification, the wave transmitter 11 and the wave receiver 13 maybe configured so that the transmission fan-shaped space T1 is fullylocated forward or front side in the rotating direction of the motor 16(the first direction K1) in the reception fan-shaped space R1, when themotor 16 rotates in the first direction K1. Moreover, in thismodification, the wave transmitter 11 and the wave receiver 13 may beconfigured so that the transmission fan-shaped space T1 is located inthe forward half or front half side of the reception fan-shaped space R1in the rotating direction of the motor 16 in the second plane P2, whenthe motor 16 rotates in the first direction K1.

Further, a relation different from the relation illustrated in FIG. 4Bmay be established. FIG. 4C is a view illustrating a furthermodification of the relation between the transmission fan-shaped spaceT1 and the reception fan-shaped space R1 in the second plane P2. In themodification illustrated in FIG. 4C, the transmission fan-shaped spaceT1 may further be offset forward or front side in the first direction K1in the reception fan-shaped space R1, compared with the modificationillustrated in FIG. 4B. In more detail, in the modification illustratedin FIG. 4C, the first transmission edge Te1 and the first reception edgeRe1 which are the leading edges of the transmission fan-shaped space T1and the reception fan-shaped space R1 in the first direction K1 may beoverlapped with each other in the second plane P2. That is, the wavetransmitter 11 and the wave receiver 13 may be configured so that thetransmission edge Te1 which is one of the pair of the transmission edgesTe1 and Te2 of the transmission fan-shaped space T1 is located at theleading reception edge Re1 of the reception fan-shaped space R1 in therotating direction of the motor 16 (the first direction K1), when themotor 16 rotates in the first direction K1 (the given direction). Withsuch a configuration, in this modification, the wave transmitter 11 andthe wave receiver 13 may be configured so that the transmissionfan-shaped space T1 is located forward or front end side in the rotatingdirection of the motor 16 (the first direction K1) in the receptionfan-shaped space R1, when the motor 16 rotates in the first directionK1. In addition, in this modification, the wave transmitter 11 and thewave receiver 13 may be configured so that the transmission fan-shapedspace T1 is located in the forward half or front half side of thereception fan-shaped space R1 in the rotating direction of the motor 16(the first direction K1) in the second plane P2, when the motor 16rotates in the first direction K1.

Next, a configuration of the transceiving part 6 is described. Referringto FIG. 1, the transceiving part 6 may include a transmitting part 21(which may also be referred to as a transmission circuitry 21) and areceiving part 22 (which may also be referred to as a receptioncircuitry 22).

The transmitting part 21 may amplify a transmission pulse signalgenerated by the signal processor 3, and apply the amplified signal tothe wave transmitter 11 as an amplified transmission pulse signal.Therefore, from the wave transmitter 11, the transmission pulse waves(transmission waves) corresponding to the respective amplifiedtransmission pulse signals may be transmitted. In detail, in thisembodiment, from the wave transmitter 11, a first transmission pulsewave corresponding to a first amplified transmission pulse signal, asecond transmission pulse wave corresponding to a second amplifiedtransmission pulse signal, and a third transmission pulse wavecorresponding to a third amplified transmission pulse signal may betransmitted with a given time interval therebetween. The frequencies ofthe first to third transmission pulse waves may be different from eachother.

The receiving part 22 may amplify the echo signal as an electric signaloutputted from the wave receiver 13, and carry out an A/D conversion ofthe amplified echo signal. Then, the receiving part 22 may output theecho signal converted into the digital signal to the signal processor 3.In more detail, the receiving part 22 may have a plurality of receptioncircuitry. Each reception circuitry may perform the given processingdescribed above to the corresponding echo signal (reception signal)acquired by converting the reception wave received by the correspondingwave receiving element 13 a into the electric signal, and then outputthe corresponding echo signal to the signal processor 3.

[Configuration of Display Unit]

The display unit 4 may display on a display screen an image according toan image data outputted from the signal processor 3. In this embodiment,the display unit 4 may display an underwater state below the shipthree-dimensionally as a bird's-eye view. Therefore, the user can guessthe underwater state below the ship (e.g., the existence and thepositions of a single fish and a school of fish, ups and downs of aseabed, and a structure such as an artificial fish reef) by looking atthe display screen.

[Configuration of Signal Processor]

FIG. 5 is a block diagram illustrating a configuration of the signalprocessor 3. Referring to FIGS. 1 and 5, the signal processor 3 maygenerate the transmission pulse signal as the transmission signal, andinput it into the transmitting part 21. Moreover, the signal processor 3may process the echo signal outputted from the receiving part 22, andgenerate the image data of the target object.

The signal processor 3 may include a controller 31, a transmissiontiming controller 32, a transmission signal generating module 33, afilter coefficient generating module 34, an echo signal acquiring module35, a fan area detection data generating module 36 as an image datagenerating module, and a three-dimensional echo data processing module37 as a synthetic image data generating module.

The signal processor 3 may be comprised of devices, such as a hardwareprocessor 39 (a CPU, a FPGA, etc.) and a nonvolatile memory, and is oneexample of a “processing circuitry” of the present disclosure. Forexample, the CPU reads the program from the nonvolatile memory andexecutes it to make the signal processor 3 function as the controller31, the transmission timing controller 32, the transmission signalgenerating module 33, the filter coefficient generating module 34, theecho signal acquiring module 35, the fan area detection data generatingmodule 36, and the three-dimensional echo data processing module 37.

The controller 31 may output a variety of information to thetransmission timing controller 32, the transmission signal generatingmodule 33, and the filter coefficient generating module 34.

The controller 31 may notify to the transmission timing controller 32timings at which the transmission timing controller 32 is to outputfirst to third transmitting triggers.

Moreover, the controller 31 may output information on frequency bands ofthe first to third transmission pulse signals to be generated by thetransmission signal generating module 33 to the transmission signalgenerating module 33 and the filter coefficient generating module 34.The controller 31 may output a first frequency band, a second frequencyband, and a third frequency band which are three frequency bandsdifferent from each other, as the frequency bands of the firsttransmission pulse signal, the second transmission pulse signal, and thethird transmission pulse signal, respectively, to the transmissionsignal generating module 33 and the filter coefficient generating module34.

Moreover, the controller 31 may output a filter specification forgenerating a filter coefficient used by the filtering performed by theecho signal acquiring module 35 to the filter coefficient generatingmodule 34. Such a filter specification may include a center frequency ofa passband, a bandwidth of the passband, a reduction level of a cutoffband, and a filter length.

The transmission timing controller 32 may generate the first to thirdtransmitting triggers at the timings instructed from the controller 31,and then sequentially output the transmitting triggers to thetransmission signal generating module 33 and the echo signal acquiringmodule 35.

Each time the transmission signal generating module 33 receives thefirst to third transmitting triggers, it may generate the firsttransmission pulse signal, the second transmission pulse signal, and thethird transmission pulse signal corresponding to the trigger signals inthis order, and then output them to the transmitting part 21. The firstto third transmission pulse signals outputted to the transmitting part21 may be amplified by the transmitting part 21, and they may betransmitted from the wave transmitter 11 as the first to thirdtransmission pulse waves, respectively.

The filter coefficient generating module 34 may generate the filtercoefficients for extracting the first to third echo signals obtainedfrom the respective reception waves as the reflection waves of the firstto third transmission pulse waves, based on the information on the firstto third frequency bands and the filter specification which are notifiedfrom the controller 31.

The controller 31 may output an instruction signal to the motor 16 tocontrol operation of the motor 16. In this embodiment, the controller 31may control the rotating direction, the rotating speed, and therotational position of the motor 16. That is, the controller 31 maycontrol the rotating direction, the rotating speed, and the rotationalposition of the wave transmitter 11 and the wave receiver 13. Thecontroller 31 may set a target output value according to a givenoperational condition. Then, the controller 31 may cause the rotationalangle detecting part 18 to detect the rotational position of the outputshaft 16 a of the motor 16, and control the motor 16 so that a deviationof the detected value and the target output value becomes zero.

The echo signal acquiring module 35 may acquire the echo signal in eachfrequency band from the echo signal outputted from the wave receiver 13.The echo signal acquiring module 35 may have same number of echo signalextracting module 38 as the number of wave receiving elements 13 aprovided to the wave receiver 13. The echo signal extracting modules 38may be provided corresponding to the respective wave receiving elements13 a.

The processings performed by the echo signal extracting modules 38 maybe the same except for the wave receiving elements 13 a from which theecho signals are outputted being different from each other, and the echosignals outputted through the channels CHm (here, m=1, 2, . . . , M)from the wave receiving elements 13 a being different from each other.

The fan area detection data generating module 36 may perform a beamforming based on M echo signals acquired from the echo signal extractingmodules 38. A case where the delay-and-sum is performed is described asone example of the beam forming. The reception beam RB can be formed byadding the echo signals after a given phase rotation is applied to eachecho signal. By changing an amount of the phase rotation applied to eachecho data to change the directivity of the reception beam RB in thereception fan-shaped space R1 (i.e., by scanning electronically), theecho intensity at each angle about a horizontal axis perpendicular tothe rotation axis L1 can be obtained. The fan area detection datagenerating module 36 can calculate the echo intensity at each positionin a range specified by a distance r from the ship and the angle aboutthe horizontal axis, by obtaining the echo intensity at each angle aboutthe horizontal axis in the distance r. Note that, below, the echointensity may also be referred to as the “fan area echo intensity.”

Then, the fan area detection data generating module 36 may calculate thefan area echo intensity at each of a plurality of angle positions aboutthe rotation axis L1, where the reception fan-shaped space R1 can belocated by being rotated by the motor 16, and may generate a pluralityof image data based on the fan area echo intensities.

The three-dimensional echo data processing module 37 may synthesize theimage data at every angle position about the rotation axis L1 generatedby the fan area detection data generating module 36 to generatesynthetic image data. This synthetic image data may be outputted to thedisplay unit 4. Then, the display unit 4 may display an image specifiedby the synthetic image data.

With the above configuration, the underwater detection apparatus 1 candetect the target object in the three-dimensional space covering thelarge area centering on the ship S, and estimate the three-dimensionalposition of the target object in this space.

Moreover, by the underwater detection apparatus 1 operating as describedabove, an underwater detection method of this embodiment may beimplemented. That is, in the underwater detection method implemented byoperating the underwater detection apparatus 1, first, the transmissionwave may be transmitted to the given transmission fan-shaped space T1having the first transmitting width Tθ1 in the given first plane P1 andhaving the second transmitting width Tθ2 in the second plane P2perpendicular to the first plane P1. Further, the reflection wave of thetransmission wave may be received, as the reception wave, in the givenreception fan-shaped space R1 which has the first receiving width Rθ1 inthe first plane P1 and the second receiving width Rθ2 in the secondplane P2, and where the second receiving width Rθ2 is larger than thesecond transmitting width Tθ2. Further, the underwater detection methodof this embodiment may be configured so that the transmission fan-shapedspace T1 is disposed in the reception fan-shaped space R1 in the secondplane P2, and the transmission fan-shaped space T1 and the receptionfan-shaped space R1 are rotated.

[Effects]

As described above, according to the underwater detection apparatus 1according to this embodiment, the second receiving width Rθ2 of thereception fan-shaped space R1 may be wider than the second transmittingwidth Tθ2 of the transmission fan-shaped space T1, and in the secondplane P2, the transmission fan-shaped space T1 may be located in thereception fan-shaped space R1. With this configuration, even if when thetransmission fan-shaped space T1 and the reception fan-shaped space R1are rotated at high speed, the reception wave corresponding to thetransmission pulse wave (transmission wave) transmitted from the wavetransmitter 11 to the transmission fan-shaped space T1 can be receivedby the reception fan-shaped space R1 of the wider second receiving widthRθ2, after the sufficient time from the start of the transmission of thetransmission pulse wave. As a result, compared with the configuration inwhich the signals received by the reception fan-shaped space R1 areincreased simply by widening the second transmitting width Tθ2 of thetransmission fan-shaped space T1, the second transmitting width Tθ2 ofthe transmission fan-shaped space T1 can be narrowed. By narrowing thesecond transmitting width Tθ2, since the transmission pulse wave canreach a more distant location, the reduction in the maximum detectionrange can be prevented. Further, even if the second transmitting widthTθ2 of the transmission fan-shaped space T1 is narrowed, since thereception wave can promptly be received, the transmitting cycle of thetransmission fan-shaped space T1, i.e., the updating cycle of thedetection result image can further be shortened. As a result, theunderwater detection apparatus 1 capable of achieving both the speed-upof the updating cycle of the detection result image and the preventionof the reduction in the detection range can be achieved.

Moreover, according to the underwater detection apparatus 1, the secondtransmitting width Tθ2 of the transmission fan-shaped space T1 cangreatly be narrowed compared with the conventional underwater detectionapparatus. As a result, since the wave transmission sensitivity of thewave transmitter 11 can be increased, the detection range can further beexpanded. Further, since the second transmitting width Tθ2 is narrow,drive time of the wave transmitter 11 can further be shortened. As aresult, amount of heat resulting from the transmitting operation canfurther be lessened.

Moreover, according to the underwater detection apparatus 1, when themotor 16 rotates in the first direction K1, the transmission fan-shapedspace T1 may be located forward or front side in the first direction K1in the reception fan-shaped space R1 in the second plane P2. With thisconfiguration, the transmission fan-shaped space T1 can be disposedforward or front side in the rotating direction of the motor 16 in thereception fan-shaped space R1. As a result, the second transmittingwidth Tθ2 of the transmission fan-shaped space T1 can further benarrowed, while more reliably suppressing occurrence of receptionleakage of the transmission pulse wave in the reception fan-shaped spaceR1.

Moreover, according to the underwater detection apparatus 1, the motor16 may rotate the wave receiver 13 in the direction perpendicular to theplane in which the beam forming is performed. Therefore, the underwaterthree-dimensional range can be detected appropriately.

[First Modification of First Embodiment]

FIG. 6 is a plan view schematically illustrating a substantial part of afirst modification of the first embodiment. Note that, below,differences from the above embodiment will mainly be described. Likereference characters are denoted in the figures to similarconfigurations as this embodiment to omit the detailed description.

In the first embodiment, the rotating direction of the motor 16 may befixed in the first direction K1. The underwater detection may beperformed by the underwater detection apparatus 1 in all the rangesabout the rotation axis L1. However, the underwater detection may beperformed only in a partial range about the rotation axis L1 (e.g., asector range of 90° or 180°). In such a case, if the motor 16 rotatesalso in the non-detecting range about the rotation axis L1 similarly tothe detection range, a dead time may occur. A configuration forshortening such a dead time may be adopted in this first modification ofthe first embodiment. That is, a configuration for increasing the imageupdate cycle may be adopted.

Referring to FIGS. 1 and 6, according to the configuration in the firstmodification of the first embodiment, the underwater detection apparatus1 may increase the rotating speed of the motor 16 in a non-detectingmode other than when displaying the image in a sector detecting mode.Thus, the image update cycle in this modification can be increased morethan the image update cycle during all-direction detection.

In this modification, (1) in the sector detecting mode, the motor 16 mayrotate at a first speed V1 to mechanically scan a detection area S1→(2)in the non-detecting mode, the motor 16 may rotate at a second speed V2faster than the first speed V1 (at this time, the image is notupdated)→(1)→(2) may be repeated.

In the following, otherwise described in particular, a state where thesecond plane P2 is seen from above as illustrated in FIG. 6 isdescribed. In this modification, the detection area S1 and anon-detection area S2 may be set. Data indicative of the detection areaS1 and the non-detection area S2 may be stored in the memory etc. of thesignal processor 3. One or more kinds of detection area S1 may be setwhen the underwater detection apparatus 1 is shipped out from a factory,or may be arbitrarily set by the user of the underwater detectionapparatus 1.

For example, in this modification, the detection area S1 and thenon-detection area S2 may be each set so as to extend in a range of 180°about the rotation axis L1. The controller 31 may perform the samedetection as described in the first embodiment when the underwaterdetection is performed in the detection area S1. On the other hand, thecontroller 31 may rotate the motor 16 but suspend the image datageneration when not detecting in the non-detection area S2.

In this modification illustrated in FIG. 6, the rotating direction ofthe motor 16 may be the first direction K1 and it may be fixed. Thecontroller 31 may rotate the motor 16 in the first direction K1 at thegiven first speed V1 when the underwater detection is performed usingthe wave transceiving unit 5 (i.e., when the underwater detection isperformed by the wave transmitter 11 and the wave receiver 13), androtate the motor 16 at the second speed V2 faster than the first speedV1 when the underwater detection is not performed.

FIG. 7 is a flowchart illustrating one example of processing in thefirst modification of the first embodiment illustrated in FIG. 6. Below,a case where the detection is performed from a starting point S1 a ofthe detection area S1 is described as one example. Referring to FIGS. 1,6, and 7, the controller 31 may perform the detection control, whilerotating the motor 16 in the first direction K1 at the first speed V1 bycontrolling the motor 16 etc. (Step S11). Therefore, the transmissionpulse wave may be transmitted from the wave transmitter 11 to thetransmission fan-shaped space T1, and the reflection wave in thereception fan-shaped space R1 is received by the wave receiver 13 as thereception wave.

Then, the controller 31 may refer to the rotational position of themotor 16 indicated by the rotational angle detecting part 18 anddetermine whether the detection is performed up to a terminal point S1 bof the detection area S1 in the first direction K1 (Step S12). If (NO atStep S12), the control at Step S11 may be repeated. On the other hand,if the detection is performed up to the terminal point S1 b of thedetection area S1 (YES at Step S12), the controller 31 may go into thenon-detecting mode (Step S13). In the non-detecting mode, for example,the controller 31 may rotate the motor 16 in the first direction K1 atthe second speed V2 faster than the first speed V1, and suspend theimage data generation (Step S13).

Note that, in the non-detecting mode, the transmission pulse wave may beor may not be transmitted from the wave transmitter 11. Moreover, in thenon-detecting mode, the reception may be or may not be performed by thewave receiver 13. The operation patterns of the wave transmitter 11 andthe wave receiver 13 in the non-detecting mode may be the following fourpatterns. That is, the patterns may be (1) the wave receiver 13 is ONwhen the wave transmitter 11 is turned ON, (2) the wave receiver 13 isOFF when the wave transmitter 11 is turned ON, (3) the wave receiver 13is ON when the wave transmitter 11 is turned OFF, and (4) the wavereceiver 13 is OFF when the wave transmitter 11 is turned OFF.

The controller 31 may repeat the control at Step S13 until the motor 16,the wave transmitter 11, and the wave receiver 13 reach the startingpoint S1 a of the detection area 51 about the rotation axis L1 (NO atStep S14), while referring to the rotational position of the motor 16indicated by the rotational angle detecting part 18. That is, thenon-detecting mode at Step S13 may be maintained. Then, if the motor 16,the wave transmitter 11, and the wave receiver 13 reach to the startingpoint S1 a of the detection area S1 about the rotation axis L1 (YES atStep S14), unless the power of the underwater detection apparatus 1 isturned OFF (NO at Step S15), the processings at and after Step S11 maybe repeated.

As described above, according to the first modification of the firstembodiment, the motor 16 may rotate at the first speed V1 when theunderwater detection is performed, and the motor 16 may rotate at thesecond speed V2 faster than the first speed V1 when the underwaterdetection is not performed. According to this configuration, theunderwater detection apparatus 1 can secure a sufficient time forreceiving the reception wave when the underwater detection is performed,and quickly return the wave transmitter 11 and the wave receiver 13 backinto the detection area S1 when the detection is not performed. As aresult, the updating cycle of the detection result image can be speededup.

Moreover, according to the first modification of the first embodiment,the controller 31 may rotate the motor 16 in the first direction K1 bothwhen the underwater detection is performed and when the underwaterdetection is not performed. According to this configuration, since it isnot necessary to change the rotating direction of the motor 16 betweenwhen the underwater detection is performed and when the detection is notperformed, the load of the motor 16 can be lowered. Moreover, therotating speed of the motor 16 can be changed more quickly between thefirst speed V1 and the second speed V2.

Moreover, according to the first modification of the first embodiment,the transmission fan-shaped space T1 may be located in the receptionfan-shaped space R1. Moreover, the controller 31 may rotate the motor 16at the first speed V1 when the underwater detection is performed, androtate the motor 16 at the second speed V2 faster than the first speedV1 when the underwater detection is not performed. According to thisconfiguration, the updating cycle of the detection result image can bespeeded up, while suppressing reception leakage of the transmission wavein the reception fan-shaped space R1.

[Second Modification of First Embodiment]

FIG. 8 is a plan view schematically illustrating a substantial part of asecond modification of the first embodiment. Note that, below, adifference from the above embodiment and the modification will mainly bedescribed, and like reference characters are denoted in the figures tosimilar configurations as this embodiment and the modification to omitthe detailed description.

The difference of the second modification of the first embodiment fromthe first modification of the first embodiment is that the controller 31rotates the motor 16 in the first direction K1 at the first speed V1during the underwater detection when the underwater detection isperformed in the detection area S1, and rotates the motor 16 in a seconddirection K2 opposite from the first direction K1 at the second speed V2during the non-detection when the underwater detection is not performed.

FIG. 9 is a flowchart illustrating one example of processing in thesecond modification of the first embodiment illustrated in FIG. 8.Below, a case where the detection is performed from the starting pointS1 a of the detection area S1 is described as one example. Referring toFIGS. 1, 8, and 9 the controller 31 may perform the detection control,while rotating the motor 16 in the first direction K1 at the first speedV1 (Step S21). This control is the same as the control at Step S11.

Then, the controller 31 may refer to the rotational position of themotor 16 indicated by the rotational angle detecting part 18, anddetermine whether the detection is performed about the rotation axis L1up to the terminal point S1 b of the detection area S1 (Step S22). Ifthe detection has not yet performed up to the terminal point S1 b of thedetection area S1 (NO at Step S22), the control at Step S21 may berepeated. On the other hand, if the detection is performed up to theterminal point S1 b of the detection area S1 (YES at Step S22), thecontroller 31 may go into the non-detecting mode while rotating themotor 16 in the second direction K2 opposite from the first direction K1at the second speed V2 faster than the first speed V1 (Step S23). Theoperations of the wave transmitter 11 and the wave receiver 13 may bethe same as operations described at Step S13.

The controller 31 may refer to the rotational position of the motor 16indicated by the rotational angle detecting part 18, and repeat thecontrol at Step S23 until the motor 16, the wave transmitter 11, and thewave receiver 13 reach the starting point S1 a of the detection area S1about the rotation axis L1 (NO at Step S24). Then, if the motor 16, thewave transmitter 11, and the wave receiver 13 reach the starting pointS1 a of the detection area S1 about the rotation axis L1 (YES at StepS24), the processings at and after Step S21 may be repeated, unless thepower of the underwater detection apparatus 1 is turned OFF (NO at StepS25).

As described above, according to the second modification of the firstembodiment, in the non-detecting mode, the motor 16 may rotate in thesecond direction K2 opposite from the first direction K1, unlike thefirst modification of the first embodiment. With this configuration, themotor 16 may rotate so as to oscillate within an angle range of 360°.Therefore, the slip ring for continuously rotating the motor 16 in thesame direction may become unnecessary.

Second Embodiment

FIG. 10 is a block diagram illustrating a configuration of an underwaterdetection apparatus 1A according to a second embodiment of the presentdisclosure. FIGS. 11A and 11B are plan views of the ship S to which theunderwater detection apparatus 1A is mounted, seen from a directionperpendicular to the second plane P2 perpendicular to the first planeP1, where the transmission fan-shaped space T1 and the receptionfan-shaped space R1 are schematically illustrated. FIG. 11A illustratesa state where the wave transmitter 11 and the wave receiver 13 arerotated in the first direction K1, and FIG. 11B illustrates a statewhere the wave transmitter 11 and the wave receiver 13 are rotated inthe second direction K2.

Referring to FIGS. 10 to 11B, a difference of the underwater detectionapparatus 1A from the underwater detection apparatus 1 of the firstembodiment is that the motor 16 rotates both in the first direction K1and the second direction K2 opposite from the first direction K1 duringthe underwater detection. That is, the underwater detection apparatus 1Acan perform the underwater detection, while rotating a wave transceivingunit 5A in the first direction K1, and can perform the underwaterdetection, while rotating the wave transceiving unit 5A in the seconddirection K2. Further, the second embodiment may be configured so thatthe direction of the transmission fan-shaped space T1 with respect tothe reception fan-shaped space R1 (in other words, the position of thetransmission fan-shaped space T1 with respect to the receptionfan-shaped space R1) is changed, when the rotating direction of themotor 16 is reversed.

The underwater detection apparatus 1A may include a direction changemechanism 40, in addition to the configuration of the underwaterdetection apparatus 1. In detail, the underwater detection apparatus 1Amay include a transceiving device 2A, the signal processor 3, and thedisplay unit 4.

The transceiving device 2A may include a wave transceiving unit 5A andthe transceiving part 6.

The wave transceiving unit 5A may include the wave transmitter 11, thewave receiver 13, the bracket 15, the motor 16 as the rotary drivingpart, the rotational angle detecting part 18, and the direction changemechanism 40.

The direction change mechanism 40 may change the direction of thetransmission fan-shaped space T1 with respect to the receptionfan-shaped space R1 in the second plane P2. The direction changemechanism 40 may change the direction of the transmission fan-shapedspace T1 so as to be interlocked with the change in the rotatingdirection of the motor 16 about the rotation axis L1 to shift theposition of the transmission fan-shaped space T1 in the second plane P2rearward or backward in the rotating direction before the change in therotating direction. That is, the direction change mechanism 40 maychange the direction of the transmission fan-shaped space T1 so as to beinterlocked with the change in the rotating direction of the motor 16 toshift the position of the transmission fan-shaped space T1 in the secondplane P2 from the forward half or front half side of the receptionfan-shaped space R1 to the rearward half or back half side in therotating direction before the change in the rotating direction.

The direction change mechanism 40 may include a pivot 41 which supportsthe wave transmitter 11 so that the direction of the wave transmitter 11with respect to the wave receiver 13 is changeable, and a directionchange motor 42 which changes the direction of the wave transmitter 11around the pivot 41.

The pivot 41 may be a shaft part extending in the longitudinal directionof the wave transmitter 11, i.e., a direction in which the plurality ofwave transmission elements 11 a are lined up, may be supported by thebracket 15, and may rotatably support the wave transmitter 11 in theoscillating direction around the pivot 41.

The direction change motor 42 may be a motor of which the rotationalposition is controllable, such as a stepping motor, a servo motor, etc.,and may be connected to the controller 31 of the signal processor 3. Thedirection change motor 42 may include a casing supported by the bracket15, and an output shaft which extends from the casing and may be coupledto the pivot 41 directly or through a reduction mechanism (notillustrated) so that the power is transferable to the pivot 41. Withthis configuration, the direction change motor 42 can change thedirection of the wave transmitter 11 around the pivot 41.

A rotational angle detecting part 43 may be attached to the directionchange motor 42, and the rotational angle detecting part 43 may beconnected to the controller 31. For example, an encoder is used as therotational angle detecting part 43. However, without being limited tothis configuration, the signal for controlling the rotation of thedirection change motor 42 may be analyzed and the signal may beconverted into angular information. In detail, if the stepping motor isused as the direction change motor 42, the number of instruction pulsesinputted into the stepping motor may be counted, and the count may beconverted into the angular information. In the underwater detectionapparatus 1A, the direction of the wave transmitter 11 with respect tothe wave receiver 13 in the second plane P2 may be calculated based onthe rotational angle of the direction change motor 42 detected by therotational angle detecting part 43. The direction change motor 42 may becontrolled by the controller 31 of the signal processor 3.

The controller 31 may output an instruction signal to the directionchange motor 42 to control the operation of the direction change motor42. The controller 31 may set a target angle value of the output shaftof the direction change motor 42. Then, the controller 31 may detect therotational position of the output shaft of the direction change motor 42by the rotational angle detecting part 43, and control the directionchange motor 42 so that a deviation of the detected value from thetarget output value becomes zero.

FIG. 12 is a flowchart illustrating one example of processing in thesecond embodiment. Referring to FIGS. 10 to 12, first, a case where theunderwater detection is performed by rotating the wave transmitter 11and the wave receiver 13 in the first direction

K1 is considered. In this case, the direction of the wave transmitter 11with respect to the wave receiver 13 may be set by the controller 31controlling the direction change motor 42 so that the transmissionfan-shaped space T1 is located in a forward part or front side part(i.e., the forward half or front half side) of the reception fan-shapedspace R1 in the first direction K1 (Step S31). At this time, thetransmission fan-shaped space T1 and the reception fan-shaped space R1are, for example, as illustrated in FIG. 11A, and may be the same as thefurther modification of the first embodiment (the modificationillustrated in FIG. 4C). Note that, at this time, the relation betweenthe transmission fan-shaped space T1 and the reception fan-shaped spaceR1 may be the relation illustrated in FIG. 4A, or may be the relationillustrated in FIG. 4B.

Next, the controller 31 may control the transmitting part 21 and thereceiving part 22 while rotating the motor 16 in the first direction K1to emit the transmission pulse wave and receive the reception wave whilerotating the wave transmitter 11 and the wave receiver 13 in the firstdirection K1. That is, the underwater detection by the underwaterdetection apparatus 1A may be performed (Step S32).

Until the controller 31 receives a direction change instruction, forexample, by a given time being lapsed or receiving an instruction fromthe operator of the underwater detection apparatus 1A (NO at Step S33),the controller 31 may perform the underwater detection, while rotatingthe motor 16 in the first direction K1 (Step S32).

On the other hand, if the controller 31 detects the direction changeinstruction (YES at Step S33), it may suspend the underwater detection(Step S34). In detail, the controller 31 may suspend the image datageneration by the signal processor 3, while suspending the rotation ofthe motor 16.

Next, the controller 31 may set the direction of the wave transmitter 11with respect to the wave receiver 13 by controlling the direction changemotor 42 so that the transmission fan-shaped space T1 is located in arearward part (i.e., the rearward half) of the reception fan-shapedspace R1 in the first direction K1, i.e., the transmission fan-shapedspace T1 is located in a forward part or front part (i.e., the forwardhalf or front half side) of the reception fan-shaped space R1 in thesecond direction K2 (Step S35). At this time, the transmissionfan-shaped space T1 and the reception fan-shaped space R1 are, forexample, as illustrated in FIG. 11B. In detail, a relative position ofthe transmission fan-shaped space T1 and the reception fan-shaped spaceR1 may be set so that the second transmission edge Te2 of thetransmission fan-shaped space T1 and the second reception edge Re2 ofthe reception fan-shaped space R1 are overlapped with each other. Thus,the direction change mechanism 40 may change the direction of thetransmission fan-shaped space T1 so as to be interlocked with the changein the rotating direction of the motor 16 to shift the position of thetransmission fan-shaped space T1 in the second plane P2 to the trailingedge side in the rotating direction of the reception fan-shaped space R1before the rotating direction is changed. Note that the configuration ofthe direction change mechanism 40 is not limited to the configuration inwhich the position of the transmission fan-shaped space T1 in the secondplane P2 is shifted to the trailing edge side of the receptionfan-shaped space R1 in the rotating direction before the change in therotating direction. The direction change mechanism 40 may have anyconfiguration as long as the position of the transmission fan-shapedspace T1 in the second plane P2 is shifted to the rearward half or backhalf side from the forward half or front half side of the receptionfan-shaped space R1 in the rotating direction before the change in therotating direction.

Next, again referring to FIGS. 10 to 12, the controller 31 may controlthe transmitting part 21, while rotating the motor 16 in the seconddirection K2 to emit the transmission pulse wave and receive thereception wave, while rotating the wave transmitter 11 and the wavereceiver 13 in the second direction. That is, the underwater detectionby the underwater detection apparatus 1A may be performed (Step S36).

Similar to the configuration described above, until the controller 31detects the direction change instruction (NO at Step S37), it mayperform the underwater detection, while rotating the wave transmitter 11and the wave receiver 13 in the second direction K2 (Step S36).

On the other hand, if the controller 31 detects the direction changeinstruction (YES at Step S37), it may suspend the underwater detection(Step S38). In detail, the controller 31 may suspend the image datageneration by the signal processor 3 while suspending the rotation ofthe motor 16. Next, the processings at and after Step S31 may berepeated.

As described above, with the underwater detection apparatus 1A accordingto the second embodiment, the direction change mechanism 40 may beprovided. Thus, both when the wave transmitter 11 and the wave receiver13 are rotated in the first direction K1 and when they are rotated inthe second direction K2, the relative spatial relationship between thetransmission fan-shaped space T1 and the reception fan-shaped space R1can be maintained similarly. Moreover, the rotating direction of thewave transmitter 11 and the wave receiver 13 may not be only one of thefirst direction K1 and the second direction K2. Therefore, it is notnecessary to use the slip ring required when the rotating direction ofthe motor 16 is fixed.

Note that, although the second embodiment is described as the directionof the wave transmitter 11 being changed by the direction change motor42, this configuration may be altered. For example, the wave receiver 13may be rotatable around a pivot similar to the pivot 41, and thedirection of the wave receiver 13 may be changed by the direction changemotor 42. At least one of the wave transmitter 11 and the wave receiver13 may be changed in the direction by the direction change motor 42.

[First Modification of Second Embodiment]

In the second embodiment, the direction change motor 40 may be omitted,a friction generating member, such as a collar made of resin, may beprovided between the pivot 41 and the casing 11 c of the wavetransmitter 11, and a stop which regulates an amount of rotation of thewave transmitter 11 around the pivot 41 within a fixed range may beprovided. In this case, when the motor 16 changes the rotating directionto the opposite direction, the output shaft 16 a of the motor 16 may bedriven so that inertia above a given value may occur in the wavetransmitter 11 around the pivot 41. Therefore, similar to the secondembodiment, the direction of the wave transmitter 11 with respect to thewave receiver 13 can be changed by the inertia.

Although in the first modification of this second embodiment thedirection of the wave transmitter 13 is changed by the inertia, theconfiguration may be altered. For example, the wave receiver 13 may berotatable around a pivot similar to the pivot 41, and the direction ofthe wave receiver 13 may be changed by the inertia. At least one of thewave transmitter 11 and the wave receiver 13 may be changed in thedirection by the inertia.

[Second Modification of Second Embodiment]

FIG. 13 is a side view schematically illustrating a substantial part ofa second modification of the second embodiment, and a part thereof isillustrated in a cross-section. In the second modification of the secondembodiment, the direction of the transmission fan-shaped space T1 withrespect to the reception fan-shaped space R1 may be changed by rotatingthe entire of the wave transmitter 11 and the wave receiver 13.

In detail, a wave transceiving unit 5B may be provided, instead of thewave transceiving unit 5 illustrated in the first embodiment. The wavetransceiving unit 5B may include the wave transmitter 11, the wavereceiver 13, the bracket 15 which supports the wave transmitter 11 andthe wave receiver 13, the motor 16 as the rotary driving part, therotational angle detecting part 18, and a direction change mechanism40B.

The direction change mechanism 40B may include the motor 16, a powerdistribution mechanism 51, and a rotating mechanism 52.

In the second embodiment, the motor 16 may constitute a part of thedirection change mechanism 40B. The output shaft 16 a of the motor 16may be coupled to the power distribution mechanism 51.

The power distribution mechanism 51 may be provided in order todistribute the output of the motor 16 selectively to power for theunderwater detection and power for reversing the direction of the wavetransmitter 11 and the wave receiver 13. The power distributionmechanism 51 may include a casing 53, a driving member 54 accommodatedin the casing 53, an actuator 55 which is supported by the casing 53 anddisplaces the driving member 54, a first follower member 56 fixed to theinside of the casing 53, and a second follower member 57 accommodated inthe casing 53.

The casing 53 may be a member which is formed in a hollow box and issupported rotatably about the rotation axis L1 by a support member (notillustrated). The output shaft 16 a of the motor 16 may penetrate thecasing 53, and may be rotatable relatively to the casing 53.

For example, the driving member 54 is a clutch disk where frictionmembers are formed on the front surface and the back surface thereof.For example, an inner spline is formed at the center of the drivingmember 54, and the inner spline may fit onto an outer spline formed onthe output shaft 16 a of the motor 16. Therefore, the driving member 54may be integrally rotatable with the output shaft 16 a and may berelatively displaceable in the axial direction of the output shaft 16 a.

The actuator 55 may displace the driving member 54 in the axialdirection of the output shaft 16 a to switch between a state where thedriving member 54 and the first follower member 56 are coupled so as tointegrally be rotatable, and a state where the driving member 54 and thesecond follower member 57 are coupled so as to integrally be rotatable.The actuator 55 may have a configuration in which a ball-screw mechanismis attached to an electric motor. The actuator 55 may be driven andcontrolled by the controller 31 of the signal processor 3.

The first follower member 56 is, for example, a metal member of a diskshape which is fixed to the casing 53 and may be integrally rotatablewith the casing 53. The first follower member 56 and the driving member54 may face each other in the axial direction of the output shaft 16 a.The second follower member 57 is, for example, a metal member of a diskshape. The second follower member 57 and the driving member 54 may faceeach other in the axial direction of the output shaft 16 a. The secondfollower member 57 may be coupled to a drive gear part 58 of therotating mechanism 52.

The rotating mechanism 52 may be provided in order to rotate the wavetransmitter 11 and the wave receiver 13 horizontally or with some anglefrom the horizontal plane. The rotating mechanism 52 may be anintersecting axis gear mechanism, and may include the drive gear part 58fixed to the first follower member 56, and a follower gear part 59 fixedto the bracket 15.

The drive gear part 58 may be formed in a shaft shape, and may berotatably supported by the casing 53 through a bearing (not illustrated)about the rotation axis L1. The second follower member 57 may be coupledto an upper end of the drive gear part 58 so as to be integrallyrotatable. A gear may be provided to a lower end of the drive gear part58.

The follower gear part 59 may have a gear which meshes with the gear ofthe drive gear part 58. The axis of the drive gear part 58 may intersectwith the axis of the follower gear part 59, and the axis of the followergear part 59 may extend horizontally or at an inclination angle near thehorizontal direction.

The bracket 15 may be rotatably supported about the axis of the followergear part 59 through a stay 60 fixed to the casing 53 and a bearing (notillustrated).

With the above configuration, when the wave transmitter 11 and the wavereceiver 13 rotate about the rotation axis L1 for the underwaterdetection, the actuator 55 may couple the driving member 54 to the firstfollower member 56 as illustrated by solid lines. Therefore, the drivingmember 54, the first follower member 56, the casing 53, the stay 60, thebracket 15, the wave transmitter 11, and the wave receiver 13 may rotateabout the rotation axis L1 integrally with the output shaft 16 a of themotor 16.

On the other hand, when the rotating direction about the rotation axisL1 is reversed, the actuator 55 may couple the driving member 54 to thesecond follower member 57 as illustrated by two-dot chain lines whichare imaginary lines. Therefore, the casing 53 may not rotate about therotation axis L1, the drive gear part 58 may rotate with the rotation ofthe output shaft 16 a of the motor 16, and the follower gear part 59 mayrotate. As a result, the bracket 15, the wave transmitter 11, and thewave receiver 13 may rotate about the rotation axis of the follower gearpart 59. Therefore, the spatial relationship of the transmissionfan-shaped space T1 and the reception fan-shaped space R1 can beachieved, similarly to the second embodiment.

Note that, when the wave transmitter 11 and the wave receiver 13 rotatein the first direction K1 and when they rotate in the second directionK2, the direction change mechanism 40B may have the configuration withthe same relative spatial relationship of the transmission fan-shapedspace T1 and the reception fan-shaped space R1, without being limited tothe above configuration.

Third Embodiment

FIG. 14 is a block diagram illustrating a configuration of an underwaterdetection apparatus 1C according to a third embodiment of the presentdisclosure. FIG. 15 is a view schematically illustrating thetransmission beam TB formed by the wave transmitter 11, the receptionbeam RB received by the wave receiver 13, and a reception beam RB2received by a second wave receiver 14. FIG. 16 is a plan view of a shipS to which the underwater detection apparatus 1C is mounted, seen in thedirection perpendicular to the second plane P2, and where thetransmission fan-shaped space T1 formed by the wave transmitter 11, thereception fan-shaped space R1 received by the wave receiver 13, and areception fan-shaped space R2 received by the second wave receiver 14are schematically illustrated.

Referring to FIGS. 14 to 16, a difference of the underwater detectionapparatus 1C from the underwater detection apparatus 1 of the firstembodiment may be that the second wave receiver 14 (hereinafter, maysimply be referred to as “the wave receiver 14”) constituted as a secondreception transducer is provided, in addition to the wave receiver 13constituted as the reception transducer. That is, the two wave receivers13 and 14 may be provided to the underwater detection apparatus 1C. Inthe underwater detection apparatus 1C, when the wave transmitter 11 andthe wave receivers 13 and 14 rotate in the first direction K1 which is agiven direction about the rotation axis L1, the wave receiver 13 mayreceive the reception wave of the reception fan-shaped space R1, andwhen the wave transmitter 11 and the wave receivers 13 and 14 rotate inthe second direction K2 about the rotation axis L1, the second wavereceiver 14 may receive the reception wave of the reception fan-shapedspace R2.

A wave transceiving unit 5C may include the wave transmitter 11, thewave receiver 13, the second wave receiver 14, the bracket 15 whichsupports the wave transmitter 11 and the wave receivers 13 and 14, themotor 16 as the rotary driving part, and the rotational angle detectingpart 18.

The second wave receiver 14 may be disposed so that wave transmitter 11is disposed between the wave receiver 13 and the second wave receiver14. The second wave receiver 14 may have a configuration in which one ormore wave receiving elements 14 a as the ultrasonic transducers areattached to a casing 14 c. Each wave receiving element 14 a may have awave receiving surface 14 b. The second wave receiver 14 may be attachedto the bracket 15. The wave transmitter 11 and the wave receivers 13 and14 may be integrally rotated by the motor 16 about the rotation axis L1of the motor 16.

The second wave receiver 14 may receive a signal of the second receptionfan-shaped space R2 which is a range or space where thethree-dimensional reception beam RB2 is formed. The second receptionfan-shaped space R2 may be a substantially fan-shaped beam. That is, thesecond wave receiver 14 may receive the reflection wave of thetransmission wave in the second reception fan-shaped space R2 as thereception wave. The second reception fan-shaped space R2 may differ inthe position about the rotation axis L1 from the reception fan-shapedspace R1, however, it may have the same fan shape as the receptionfan-shaped space R1.

The second wave receiver 14 may perform the beam forming with thetransceiving part 6 and the signal processor 3 which will be describedin detail below, similar to the wave receiver 13, to detect inside thereception fan-shaped space R2 as the fan-shaped space where the lineararray of the second wave receiver 14 has the gain by using the thinreception beam which scans electronically.

The second reception fan-shaped space R2 may have a third receivingwidth Rθ3 in the first plane P1, and it may have a fourth receivingwidth Rθ4 in the second plane P2, where the third receiving width Rθ3 iswider than the fourth receiving width Rθ4. Further, the fourth receivingwidth Rθ4 of the second reception fan-shaped space R2 may be wider thanthe second transmitting width Tθ2 of the transmission fan-shaped spaceT1 (i.e., Rθ4>Tθ2). The second reception fan-shaped space R2 may beformed in the fan shape both in the first plane P1 and the second planeP2. The third receiving width Rθ3 may be an angle width about thehorizontal axis centering on the second wave receiver 14. The fourthreceiving width Rθ4 may be an angle width about the rotation axis L1 ofthe motor 16.

Note that, as described above, when the reception power sensitivity atedges Re3 and Re4 of the second reception fan-shaped space R2 is themagnitude of −3 dB from the reception power sensitivity at a center axisR2 x, the fourth receiving width Rθ4<the third receiving width Rθ3. Onthe other hand, for example, when the reception power sensitivity at theedges Re3 and Re4 of the reception fan-shaped space R2 is the magnitudeof −10 dB (i.e., smaller than −3 dB) from the reception powersensitivity at the center axis R2 x, the fourth receiving width Rθ4 maybe larger than the third receiving width Rθ3.

The third receiving width Rθ3 may be within a range of 6° to 90°.Although the fourth receiving width Rθ4 is, for example, 36°, it may bean angle less than 90° as long as it is larger than the secondtransmitting width Tθ2, without being limited to this configuration.Note that, in this embodiment, the fourth receiving width Rθ4 and thesecond receiving width Rθ2 may be set as the same value.

An angle formed by the direction which is perpendicular to the wavereceiving surface 14 b of the linear array and where the secondreception fan-shaped space R2 is formed, and the horizontal plane, maybe any angle, as long as it is within a range from 0° which is an anglein case where the linear array is disposed in the vertical direction to90° which is an angle in case where the linear array is disposed in thehorizontal direction.

About the rotation axis L1 in the second plane P2, the center axis R2 xof the second reception fan-shaped space R2 may be a line on which thereception power sensitivity is the highest in the second receptionfan-shaped space R2. On the other hand, about the rotation axis L1 inthe second plane P2, the third reception edge Re3 and the fourthreception edge Re4 as a pair of edges of the second reception fan-shapedspace R2 may be lines at positions where the reception power sensitivityis the lowest in the second reception fan-shaped space R2. In thisembodiment, the reception power sensitivity at the reception edges Re3and Re4 may be an intensity of −3 dB from the reception powersensitivity at the center axis R2 x, and may be a substantially half ofthe intensity. The second reception fan-shaped space R2 may be a rangeor space which includes the center axis R2 x at which the receptionpower sensitivity of the second reception fan-shaped space R2 is themaximum, and where the reception power sensitivity is halved from themaximum to −3 dB. In this embodiment, the second wave receiver 14 may beprovided to the bottom of the ship so that the center axis R2 x of thesecond reception fan-shaped space R2 becomes obliquely to the verticaldirection. Note that the second reception fan-shaped space R2 may be arange where the reception power sensitivity is reduced by −n3 dB (n3 isset according to the detection target object etc. of the underwaterdetection apparatus 1C) from the maximum value. The third reception edgeRe3 may be a leading edge or front edge in the first direction K1, andthe fourth reception edge Re4 may be a trailing edge in the firstdirection K1.

In this embodiment, in the second plane P2, the transmission fan-shapedspace T1 may be located in the reception fan-shaped space R1 and may bealso located in the second reception fan-shaped space R2. That is, thetransmission fan-shaped space T1 may be located so as to be included inthe reception fan-shaped space R1 and also included in the secondreception fan-shaped space R2. In detail, in the second plane P2, boththe pair of the transmission edges Te1 and Te2 of the transmissionfan-shaped space T1 may be located in the reception fan-shaped space R1,and may be also located in the second reception fan-shaped space R2.

Moreover, in this embodiment, the wave transmitter 11, the wave receiver13, and the second wave receiver 14 may be configured so that thetransmission fan-shaped space T1 is located in a forward part or frontpart of the reception fan-shaped space R1 in the rotating direction ofthe motor 16 (the first direction K1), and is located in a rearward partof the second reception fan-shaped space R2 in the rotating direction ofthe motor 16 (the first direction K1), when the motor 16 rotates in thefirst direction K1 (the given direction). That is, in the second planeP2, the wave transmitter 11, the wave receiver 13, and the second wavereceiver 14 may be configured so that the transmission fan-shaped spaceT1 is located in the forward half or front half side of the receptionfan-shaped space R1 and is located in the rearward half or back halfside of the second reception fan-shaped space R2 in the rotatingdirection of the motor 16 (the first direction K1), when the motor 16rotates in the first direction K1 (the given direction). In addition,the wave transmitter 11, the wave receiver 13, and the second wavereceiver 14 may be configured so that the transmission fan-shaped spaceT1 is located in a forward part or front part of the second receptionfan-shaped space R2 in the rotating direction of the motor 16 (thesecond direction K2), and is located in a rearward part of the receptionfan-shaped space R1 in the rotating direction of the motor 16 (thesecond direction K2), when the motor 16 rotates in the second directionK2 opposite from the first direction. That is, in the second plane P2,the wave transmitter 11, the wave receiver 13, and the second wavereceiver 14 may be configured so that the transmission fan-shaped spaceT1 is located in the forward half or front half side of the secondreception fan-shaped space R2 and is located in the rearward half orback half side of the reception fan-shaped space R1 in the rotatingdirection of the motor 16 (the second direction K2), when the motor 16rotates in the second direction K2.

In this embodiment, in the second plane P2, the first transmission edgeTe1 and the first reception edge Re1 which are the leading edges of thetransmission fan-shaped space T1 and the reception fan-shaped space R1in the first direction K1, respectively, may be overlapped with eachother, and the second transmission edge Te2 and the fourth receptionedge Re4 which are the trailing edges of the transmission fan-shapedspace T1 and the second reception fan-shaped space R2 in the firstdirection K1, respectively, may be overlapped with each other. Inaddition, in the second plane P2, the second transmission edge Te2 andthe fourth reception edge Re4 which are the leading edges of thetransmission fan-shaped space T1 and the second reception fan-shapedspace R2 in the second direction K2, respectively, may be overlappedwith each other, and the first transmission edge Te1 and the firstreception edge Re1 which are the trailing edges of the transmissionfan-shaped space T1 and the reception fan-shaped space R1 in the seconddirection K2, respectively, may be overlapped with each other. That is,when the motor 16 rotates in the first direction K1, the leadingtransmission edge Te1 of the pair of the transmission edges Te1 and Te2of the transmission fan-shaped space T1 in the rotating direction of themotor 16 (the first direction K1) may be located at the leadingreception edge Re1 of the reception fan-shaped space R1 in the rotatingdirection of the motor 16 (the first direction K1). Further, when themotor 16 rotates in the second direction K2, the leading transmissionedge Te2 of the pair of the transmission edges Te1 and Te2 of thetransmission fan-shaped space T1 in the rotating direction of the motor16 (the second direction K2) may be located at the leading receptionedge Re4 of the second reception fan-shaped space R2 in the rotatingdirection of the motor 16 (the second direction K2). Therefore, in thisembodiment, the wave transmitter 11, the wave receiver 13, and thesecond wave receiver 14 may be configured so that the transmissionfan-shaped space T1 is located in the forward part or front edge part ofthe reception fan-shaped space R1 in the rotating direction of the motor16 (the first direction K1), when the motor 16 rotates in the firstdirection K1, and is located in the forward part or front end part ofthe second reception fan-shaped space R2 in the rotating direction ofthe motor 16 (the second direction K2), when the motor 16 rotates in thesecond direction K2.

Referring again to FIGS. 14 to 16, the motor 16 may rotate the wavetransmitter 11, the wave receiver 13, and the second wave receiver 14integrally in the first direction K1 or the second direction K2 aboutthe rotation axis L1. That is, the motor 16 may rotate the transmissionfan-shaped space T1, the reception fan-shaped space R1, and the secondreception fan-shaped space R2.

The receiving part 22 of the transceiving part 6 may be connected withthe wave receiver 13 and the second wave receiver 14, may amplify theecho signal as the electric signal outputted selectively from one of thewave receivers 13 and 14, and may carry out the A/D conversion of theamplified echo signal. Then, the receiving part 22 may output the echosignal converted into the digital signal to the signal processor 3. Indetail, the receiving part 22 may have a plurality of receptioncircuitries. Each reception circuitry may output to the signal processor3 each echo signal (reception signal) acquired by converting thereception wave received by the wave receiving element 13 a or 14 a intothe electric signal.

The controller 31 of the signal processor 3 may selectively receive fromthe transceiving part 6 the echo signal from the wave receiver 13 or theecho signal from the second wave receiver 14. Then, the signal processor3 may generate the image data as the detection information based on theecho signal (i.e., the reception signal) from the wave receiver 13 orthe echo signal (i.e., the second reception signal) from the second wavereceiver 14.

With the above configuration, in this embodiment, the receiving part 22may constitute the reception circuitry which generates the receptionsignal as the echo signal from the reception wave received by the wavereceiver 13, and generate the second reception signal as the echo signalfrom the reception wave received by the second wave receiver 14. Thesignal processor 3 including the hardware processor 39 may constitutethe processing circuitry which generates the detection information asthe image data based on the reception signal and the second receptionsignal.

Moreover, in this embodiment, when the signal processor 3 rotates thewave transmitter 11 and the wave receivers 13 and 14 in the firstdirection K1 in the detection area S1, it may transmit the transmissionpulse wave from the wave transmitter 11 to the transmission fan-shapedspace T1, and perform the beam forming, for the reception wave receivedby the wave receiver 13, by using the reception result in the receptionfan-shaped space R1 to generate the image data indicative of thedetection result. That is, in this embodiment, when the motor 16 rotatesin the given first direction K1, the signal processor 3 as theprocessing circuitry may generate the detection information as the imagedata based on the reception signal as the echo signal generated from thereception wave received by the wave receiver 13. Note that, at thistime, the signal of the second reception fan-shaped space R2 may not beused for the image data generation.

On the other hand, when the signal processor 3 rotates the wavetransmitter 11 and the wave receivers 13 and 14 in the second directionK2 in the detection area S1, it may transmit the transmission pulse wavefrom the wave transmitter 11 to the transmission fan-shaped space T1,and perform the beam forming, for the reception wave received by thesecond wave receiver 14, by using the reception result in the secondreception fan-shaped space R2 to generate the image data indicative ofthe detection result. That is, in this embodiment, when the motor 16rotates in the second direction K2 different from the first directionK1, the signal processor 3 as the processing circuitry may generate thedetection information as the image data based on the second receptionsignal as the echo signal generated from the reception wave received bythe second wave receiver 14. Note that, at this time, the signal of thereception fan-shaped space R1 may not be used for the image datageneration.

According to the configuration of the wave transceiving unit 5C, theunderwater detection apparatus 1C can detect the target object in thethree-dimensional space covering the large area centering on the ship S,and estimate the three-dimensional position of the target object in thisspace.

As described above, according to the underwater detection apparatus 1Cof the third embodiment, the underwater detection can be performed evenwhen the wave transmitter 11 and the wave receivers 13 and 14 rotateeither in the first direction K1 or the second direction K2. As aresult, the motor 16 can also rotate so as to oscillate within an anglerange of 360°. Therefore, the slip ring may become unnecessary. Further,the operation for physically reversing the wave transmitter 11 and thewave receivers 13 and 14 may be unnecessary.

[Modification of Third Embodiment]

FIG. 17 is a block diagram illustrating a configuration of an underwaterdetection apparatus 1D according to a modification of the thirdembodiment of the present disclosure. FIG. 18 is a view schematicallyillustrating the transmission beam TB formed by the wave transmitter 11,a transmission beam TB2 formed by a second wave transmitter 12, and thereception beam RB received by the wave receiver 13. FIG. 19 is a planview of the ship S to which the underwater detection apparatus 1D ismounted, seen in the direction perpendicular to the second plane P2,where the transmission fan-shaped space T1 formed by the wavetransmitter 11, a second transmission fan-shaped space T2 formed by thesecond wave transmitter 12, and the reception fan-shaped space R1received by the wave receiver 13 are schematically illustrated.

Referring to FIGS. 17 to 19, a difference of the underwater detectionapparatus 1D from the underwater detection apparatus 1C of the thirdembodiment is that the second wave transmitter 12 (hereinafter, maysimply be referred to as “the wave transmitter 12”) constituted as asecond transmission transducer is provided in addition to the wavetransmitter 11 constituted as the transmission transducer, and only onewave receiver 13 is provided. That is, the underwater detectionapparatus 1D may be provided with the two wave transmitters 11 and 12,and may also be provided with the single wave receiver 13. In theunderwater detection apparatus 1D, when the wave transmitters 11 and 12and the wave receiver 13 rotate about the rotation axis L1 in the firstdirection K1 which is the given direction, the wave transmitter 11 maytransmit the transmission pulse wave to the transmission fan-shapedspace T1. Moreover, when the wave transmitters 11 and 12 and the wavereceiver 13 rotate in the second direction K2 about the rotation axisL1, the second wave transmitter 12 may transmit the transmission pulsewave to the second transmission fan-shaped space T2.

A wave transceiving unit 5D may include the wave transmitter 11, thesecond wave transmitter 12, the wave receiver 13, the bracket 15 whichsupports the wave transmitters 11 and 12 and the wave receiver 13, themotor 16 as the rotary driving part, and the rotational angle detectingpart 18.

The second wave transmitter 12 may be disposed so that the wave receiver13 is disposed between the wave transmitter 11 and the second wavetransmitter 12. The second wave transmitter 12 may have theconfiguration in which one or more wave transmission elements 12 a asthe ultrasonic transducers are attached to a casing 12 c. Each wavetransmission element 12 a may have a second wave transmitting surface 12b. The second wave transmitter 12 may be attached to the bracket 15, andthe wave transmitters 11 and 12 and the wave receiver 13 may be rotatedintegrally by the motor 16 about the rotation axis L1 of the motor 16.

The second wave transmitter 12 may form the three-dimensionaltransmission beam TB2 in the second transmission fan-shaped space T2.The second transmission fan-shaped space T2 may be the substantiallyfan-shaped beam, and may have the same shape as the transmissionfan-shaped space T1. That is, the second wave transmitter 12 maytransmit the second transmission wave into the second transmissionfan-shaped space T2. The second transmission fan-shaped space T2 may bethe range which includes the center axis T2 x at which the transmissionsignal power of the second transmission fan-shaped space T2 is themaximum, and where the transmission signal power is halved from themaximum to −3 dB. In this modification, the second wave transmitter 12may be provided to the bottom of the ship so that the center axis T2 xof the second transmission fan-shaped space T2 becomes obliquely to thevertical direction (the z-axis direction in FIG. 18). Note that thesecond transmission fan-shaped space T2 may be the range where thetransmission signal power is reduced by −n4 dB (n4 is set according tothe detection target object etc. of the underwater detection apparatus1D) from the maximum.

The second transmission fan-shaped space T2 may have a thirdtransmitting width Tθ3 in the first plane P1 and have a fourthtransmitting width Tθ4 in the second plane P2, where the thirdtransmitting width Tθ3 is wider than the fourth transmitting width Tθ4.The second transmission fan-shaped space T2 may be formed in the fanshape both in the first plane P1 and the second plane P2. The thirdtransmitting width Tθ3 may be the angle width about the horizontal axiscentering on the second wave transmitter 12. The fourth transmittingwidth Tθ4 may be the angle width about the rotation axis L1 of the motor16. Moreover, in this modification, the third transmitting width Tθ3 maybe set same as the first transmitting width Tθ1. In addition, the fourthtransmitting width Tθ4 may be set same as the second transmitting widthTθ2. In this modification, the second receiving width Rθ2 of thereception fan-shaped space R1 may be set wider than the fourthtransmitting width Tθ4 of the second transmission fan-shaped space T2(i.e., Rθ2>Tθ4). Further, in the second plane P2, the secondtransmission fan-shaped space T2 may be located inside the receptionfan-shaped space R1.

Note that, as described above, when the transmission signal power at theedges Te1 and Te2 of the transmission fan-shaped space T1 is themagnitude of −3 dB from the transmission signal power at the center axisTx, the second transmitting width Tθ2 <the first transmitting width Tθ1.On the other hand, for example, when the transmission signal power atthe edges Te1 and Te2 of the transmission fan-shaped space T1 is themagnitude of −10 dB (i.e., smaller than −3 dB) from the transmissionsignal power at the center axis Tx, the second transmitting width Tθ2may be larger than the first transmitting width Tθ1.

Moreover, as described above, when the transmission signal power at theedges Te3 and Te4 of the second transmission fan-shaped space T2 is themagnitude of −3 dB from the transmission signal power at the center axisT2 x, the fourth transmitting width Tθ4<the third transmitting widthTθ3. On the other hand, for example, when the transmission signal powerat the edges Te3 and Te4 of the second transmission fan-shaped space T2is the magnitude of −10 dB (i.e., smaller than −3 dB) from thetransmission signal power at the center axis T2 x, the fourthtransmitting width Tθ4 may be larger than the third transmitting widthTθ3.

The angle formed by the direction which is perpendicular to the wavetransmitting surface 12 b of the linear array and in which the secondtransmission fan-shaped space T2 is formed, and the horizontal plane,may be any angle, as long as it is within the range from 0° which is theangle in case where the linear array is disposed in the verticaldirection to 90° which is the angle in case where the linear array isdisposed in the horizontal direction.

About the rotation axis L1 in the second plane P2, the center axis T2 xof the second transmission fan-shaped space T2 may be a line at whichthe transmission signal power is the highest in the second transmissionfan-shaped space T2. On the other hand, about the rotation axis L1 inthe second plane P2, the third transmission edge Te3 and the fourthtransmission edge Te4 as the pair of edges of the second transmissionfan-shaped space T2 may be the lines at which the transmission signalpower is the lowest in the second transmission fan-shaped space T2. Thetransmission signal power in the transmission edges Te3 and Te4 may be ahalf of the transmission signal power at the center axis T2 x. The thirdtransmission edge Te3 may be the trailing edge of the second directionK2, and the fourth transmission edge Te4 may be the leading edge of thesecond direction K2.

In this modification, in the second plane P2, the transmissionfan-shaped space T1 may be located in the reception fan-shaped space R1,and further, the second transmission fan-shaped space T2 may also belocated in the reception fan-shaped space R1. That is, the transmissionfan-shaped space T1 may be included in the reception fan-shaped spaceR1, the second transmission fan-shaped space T2 may also be included inthe reception fan-shaped space R1. In more detail, in the second planeP2, both the pair of the transmission edges Te1 and Te2 of thetransmission fan-shaped space T1 may be located in the receptionfan-shaped space R1, both the pair of the transmission edges Te3 and Te4of the second transmission fan-shaped space T2 may be located in thereception fan-shaped space R1.

Moreover, in this modification, the wave transmitter 11, the second wavetransmitter 12, and the wave receiver 13 may be configured so that, whenthe motor 16 rotates in the first direction K1 (the given direction),the transmission fan-shaped space T1 is located in the forward part orfront part of the reception fan-shaped space R1 in the rotatingdirection of the motor 16 (the first direction K1), and the secondtransmission fan-shaped space T2 is located in the rearward part of thereception fan-shaped space R1 in the rotating direction of the motor 16(the first direction K1). That is, the wave transmitter 11, the secondwave transmitter 12, and the wave receiver 13 may be configured so that,in the second plane P2, when the motor 16 rotates in the first directionK1 (the given direction), the transmission fan-shaped space T1 islocated in the forward half or front half side of the receptionfan-shaped space R1, and the second transmission fan-shaped space T2 islocated in the rearward half or back half side of the receptionfan-shaped space R1 in the rotating direction of the motor 16 (the firstdirection K1). Further, the wave transmitter 11, the second wavetransmitter 12, and the wave receiver 13 may be configured so that, whenthe motor 16 rotates in the second direction K2 opposite from the firstdirection K1, the second transmission fan-shaped space T2 is located inthe forward part or front part of the reception fan-shaped space R1 inthe rotating direction of the motor 16 (the second direction K2), andthe transmission fan-shaped space T1 is located in the rearward part ofthe reception fan-shaped space R1 in the rotating direction of the motor16 (the second direction K2). That is, the wave transmitter 11, thesecond wave transmitter 12, and the wave receiver 13 may be configuredso that, in the second plane P2, when the motor 16 rotates in the seconddirection K2, the second transmission fan-shaped space T2 is located inthe forward half or front half side of the reception fan-shaped spaceR1, and the transmission fan-shaped space T1 is located in the rearwardhalf or back half side of the reception fan-shaped space R1 in therotating direction of the motor 16 (the second direction K2).

Moreover, in this modification, in the second plane P2, the firsttransmission edge Te1 and the first reception edge Re1 which are theleading edges of the transmission fan-shaped space T1 and the receptionfan-shaped space R1 in the first direction K1, respectively, may beoverlapped with each other, and the fourth transmission edge Te4 and thesecond reception edge Re2 which are the trailing edges of the secondtransmission fan-shaped space T2 and the reception fan-shaped space R1in the first direction K1, respectively, may be overlapped with eachother. Further, in the second plane P2, the fourth transmission edge Te4and the second reception edge Re2 which are the leading edges of thesecond transmission fan-shaped space T2 and the reception fan-shapedspace R1 in the second direction K2, respectively, may be overlappedwith each other, and the first transmission edge Te1 and the firstreception edge Re1 which are the trailing edges of the transmissionfan-shaped space T1 and the reception fan-shaped space R1 in the seconddirection K2, respectively, may be overlapped with each other. That is,when the motor 16 rotates in the first direction K1, the leadingtransmission edge Te1 of the pair of the transmission edges Te1 and Te2of the transmission fan-shaped space T1 in the rotating direction of themotor 16 (the first direction K1) may be located at the leadingreception edge Re1 of the reception fan-shaped space R1 in the rotatingdirection of the motor 16. When the motor 16 rotates in the seconddirection K2, the leading transmission edge Te4 of the pair of thetransmission edges Te3 and Te4 of the second transmission fan-shapedspace T2 in the rotating direction of the motor 16 (the second directionK2) may be located at the leading reception edge Re2 of the receptionfan-shaped space R1 in the rotating direction of the motor 16.Therefore, in this modification, the wave transmitter 11, the secondwave transmitter 12, and the wave receiver 13 may be configured so that,when the motor 16 rotates in the first direction K1, the transmissionfan-shaped space T1 is located in the forward part or front part of thereception fan-shaped space R1 in the rotating direction of the motor 16(the first direction K1), and when the motor 16 rotates in the seconddirection K2, the second transmission fan-shaped space T2 is located inthe forward part or front end part of the reception fan-shaped space R1in the rotating direction of the motor 16 (the second direction K2).

Referring again to FIGS. 17 to 19, the motor 16 may integrally rotatethe wave transmitters 11 and 12 and the wave receiver 13 in the firstdirection K1 or the second direction K2 about the rotation axis L1. Thatis, the motor 16 may rotate the transmission fan-shaped space T1, thesecond transmission fan-shaped space T2, and the reception fan-shapedspace R1.

The signal processor 3 may generate the transmission pulse signal so asto transmit the transmission pulse wave through the transmitting part 21and drive the wave transmitter 11 and the second wave transmitter 12. Inmore detail, when the signal processor 3 generates the transmissionpulse signal, the transmitting part 21 may amplify the transmissionpulse signal generated by the signal processor 3, and apply theamplified signal selectively to the wave transmitter 11 or the secondwave transmitter 12 as the amplified transmission pulse signal.Therefore, from the wave transmitter 11 or the second wave transmitter12, the transmission pulse wave corresponding to the amplifiedtransmission pulse signal may be transmitted.

With the above configuration, in this modification, the signal processor3 including the hardware processor 39 may constitute the processingcircuitry which drives the wave transmitter 11 and the second wavetransmitter 12. Moreover, in this modification, the signal processor 3as the processing circuitry may drive the wave transmitter 11 when themotor 16 rotates in the first direction K1, and drive the second wavetransmitter 12 when the motor 16 rotates in the second direction K2different from the first direction K1.

In more detail, when rotating the motor 16 in the first direction K1 androtating the wave transmitters 11 and 12 and the wave receiver 13 in thefirst direction K1 in the detection area S1, the signal processor 3 maydrive the wave transmitter 11 so that a transmission pulse wave istransmitted from the wave transmitter 11 to the transmission fan-shapedspace T1. Further, the signal processor 3 may transmit the transmissionpulse signal from the wave transmitter 11, and perform the beam forming,for the reception wave received by the wave receiver 13, by using thereception result of the reception fan-shaped space R1 to generate theimage data indicative of the detection result. At this time, thetransmission pulse wave may not be transmitted from the second wavetransmitter 12.

On the other hand, when the signal processor 3 rotates the motor 16 inthe second direction K2 and rotates the wave transmitters 11 and 12 andthe wave receiver 13 in the second direction K2 in the detection areaS1, it may drive the second wave transmitter 12 so that the transmissionpulse wave is transmitted to the second transmission fan-shaped space T2from the second wave transmitter 12. Further, the signal processor 3 maytransmit the transmission pulse signal from the second wave transmitter12, and perform the beam forming, for the reception wave received by thewave receiver 13, by using the reception result of the receptionfan-shaped space R1 to generate the image data indicative of thedetection result. At this time, the transmission pulse wave may not betransmitted from the wave transmitter 11.

According to the configuration of the wave transceiving unit 5D, theunderwater detection apparatus 1D can detect the target object in thethree-dimensional space covering the large area centering on the ship S,and estimate the three-dimensional position of the target object in thisspace.

As described above, according to the underwater detection apparatus 1Dof this modification of the third embodiment, the underwater detectioncan be performed even when the wave transmitters 11 and 12 and the wavereceiver 13 rotate either in the first direction K1 or the seconddirection K2. As a result, the motor 16 can also rotate so as tooscillate within the angle range of 360°. Therefore, the slip ring maybecome unnecessary. Further, the operation for physically reversing thewave transmitters 11 and 12 and the wave receiver 13 may be unnecessary.

[Other Modifications]

The embodiments and the modifications of the present disclosure aredescribed above. However, the present disclosure is not limited to theabove configuration, and may variously be changed or modified withoutdeparting from the scope of the present disclosure.

(1) In the embodiments and the modifications, the wave transmitters 11and 12 may have the plurality of wave transmission elements 11 a and 12a, respectively. However, this configuration may be altered. Forexample, each of the wave transmitters 11 and 12 may have a single wavetransmission element. Moreover, the wave receivers 13 and 14 may havethe plurality of wave receiving elements 13 a and 14 a, respectively.However, this configuration may be altered. For example, each wavereceiver has a single wave receiving element. When each of the wavereceivers 13 and 14 has one wave receiving element, a two-dimensionaldetection result image can be displayed on the display unit.

(2) Moreover, in the above embodiments and the above modifications, thewave transmitters 11 and 12 dedicated for transmission and the wavereceivers 13 and 14 dedicated for reception may be provided. However,this configuration may be altered. For example, a transducer having thesubstantial part illustrated in FIG. 20 as the modification may be usedto perform the transmission of the transmission pulse wave and thereception of the reflection wave. This transducer may have onepiezo-electric element 61, a pair of the reception electrodes 62provided to the front surface and the back surface of the piezo-electricelement 61, a pair of the transmission electrodes 63 provided to thefront surface and the back surface of the piezo-electric element 61, andan acoustic lens 64 provided to one of the transmission electrodes 63.The pair of the reception electrodes 62 may be connected to thereceiving part 22. Moreover, the pair of the transmission electrodes 63may be connected to the transmitting part 21.

(3) Moreover, in the above embodiments and the above modifications,although the underwater detection apparatus detects the perimeter belowthe ship S, this configuration may be altered. The present disclosure isalso applicable to other underwater detection apparatuses, such as afront detection sonar, a starboard detection sonar, and a port detectionsonar.

For example, with reference to FIG. 21 which is a view schematicallyillustrating an underwater detection apparatus 1E according to a fourthembodiment of the present disclosure, this underwater detectionapparatus 1E may be used as the front detection sonar. For example, theunderwater detection apparatus 1E may have the configuration same as anyof the underwater detection apparatuses 1, 1A, 1C, and 1D. In the fourthembodiment, the underwater detection apparatus 1E may have theconfiguration same as the underwater detection apparatus 1. Atransceiving unit 5 may be installed in the bow of the ship S.

The wave transmitter 11 of the wave transceiving unit 5 may form atransmission fan-shaped space T1E forward of the ship S. Although thetransmission fan-shaped space T1E is the same shape as the transmissionfan-shaped space T1, the direction to the seabed surface may differ.Moreover, the wave receiver 13 of the wave transceiving unit 5 mayreceive a signal from a reception fan-shaped space R1E forward of theship S. Although the reception fan-shaped space R1E is the same shape asthe reception fan-shaped space R1, the direction to the seabed surfacemay differ. In the fourth embodiment, the first plane P1 may be a planeincluding a horizontal straight line. Moreover, the second plane P2 maybe a vertical plane. Also in the fourth embodiment, similar to the firstembodiment, the wave transmitter 11 and the wave receiver 13 may beconfigured so that, in the second plane P2, the second receiving widthRθ2 of the reception fan-shaped space R1E is wider than the secondtransmitting width Tθ2 of the transmission fan-shaped space T1E, and inthe second plane P2, the transmission fan-shaped space T1E is located inthe reception fan-shaped space R1E. Moreover, in the underwaterdetection apparatus 1E, both the wave transmitting surface 11 b of thewave transmitter 11 and the wave receiving surface 13 b of the wavereceiver 13 may be disposed obliquely to a vertical plane, and adirection perpendicular to the wave transmitting surface 11 b and adirection perpendicular to the wave receiving surface 13 b may not beparallel to each other but may be different directions.

In the fourth embodiment, the transmission fan-shaped space T1E and thereception fan-shaped space R1E may rotate about a horizontal axisextending to the left and right of the ship S (the y-axis illustrated inFIG. 21). As illustrated in FIG. 21, when the reception fan-shaped spaceR1E is located above the transmission fan-shaped space T1E, the firstdirection K1 may be a direction about the y-axis from the sea surface tothe seabed. On the other hand, when the detection is performed while thereception fan-shaped space R1E is located below the transmissionfan-shaped space T1E, the second direction K2 may be a direction aboutthe y-axis from the seabed to the sea surface, and it may be oppositefrom the first direction K1.

Also in the underwater detection apparatus 1E according to the fourthembodiment, both the speed-up of the updating cycle of the detectionresult image and the prevention of the reduction in the detection rangeforward of the ship S can be achieved.

(4) Moreover, in the above embodiments and the above modifications, theecho intensity at each angle about the horizontal axis perpendicular tothe rotation axis L1 in the reception fan-shaped spaces R1 and R2 may becalculated by using the delay-and-sum as the beam forming technique inthe fan area detection data generating module 36. However, thisconfiguration may be altered. For example, the echo intensity at eachangle about the horizontal axis in the reception fan-shaped spaces R1and R2 may be calculated by using an adaptation beam forming technique,such as the Capon method and the MUSIC method. Therefore, compared withthe case where the delay-and-sum is used, an angle resolution in thedirection about the horizontal axis in this apparatus can be improved.

(5) In the above embodiments and the above modifications, although thewave transmitters 11 and 12 are each formed in the form of the lineararray, the configuration may be altered. For example, by arraying theplurality of wave transmission elements 11 a and 12 a along an arc, thetransmission fan-shaped spaces T1 and T2 can be expanded in (p-directionto detect a larger area, or the source level can be increased whilemaintaining the sizes of the transmission fan-shaped spaces T1 and T2.

(6) In the above embodiments and the above modifications, although thewave receivers 13 and 14 are each formed in the form of the lineararray, the configuration may be altered. For example, by arranging theplurality of wave receiving elements 13 a and 14 a along an arc, thereception fan-shaped spaces R1 and R2 can be expanded in the(p-direction to detect a larger area.

(7) In the above embodiments and the above modifications, although thewave transmitters 11 and 12, and the wave receivers 13 and 14 arerotated by the single motor 16, the configuration may be altered. Forexample, the wave transmitters 11 and 12, and the wave receivers 13 and14 may be rotated by separate motors.

Terminology

It is to be understood that not necessarily all objects or advantagesmay be achieved in accordance with any particular embodiment describedherein. Thus, for example, those skilled in the art will recognize thatcertain embodiments may be configured to operate in a manner thatachieves or optimizes one advantage or group of advantages as taughtherein without necessarily achieving other objects or advantages as maybe taught or suggested herein.

All of the processes described herein may be embodied in, and fullyautomated via, software code modules executed by a computing system thatincludes one or more computers or processors. The code modules may bestored in any type of non-transitory computer-readable medium or othercomputer storage device. Some or all the methods may be embodied inspecialized computer hardware.

Many other variations than those described herein will be apparent fromthis disclosure. For example, depending on the embodiment, certain acts,events, or functions of any of the algorithms described herein can beperformed in a different sequence, can be added, merged, or left outaltogether (e.g., not all described acts or events are necessary for thepractice of the algorithms). Moreover, in certain embodiments, acts orevents can be performed concurrently, e.g., through multi-threadedprocessing, interrupt processing, or multiple processors or processorcores or on other parallel architectures, rather than sequentially. Inaddition, different tasks or processes can be performed by differentmachines and/or computing systems that can function together.

The various illustrative logical blocks and modules described inconnection with the embodiments disclosed herein can be implemented orperformed by a machine, such as a processor. A processor can be amicroprocessor, but in the alternative, the processor can be acontrolling module, microcontrolling module, or state machine,combinations of the same, or the like. A processor can includeelectrical circuitry configured to process computer-executableinstructions. In another embodiment, a processor includes an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) or other programmable device that performs logic operationswithout processing computer-executable instructions. A processor canalso be implemented as a combination of computing devices, e.g., acombination of a digital signal processor (DSP) and a microprocessor, aplurality of microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration. Although describedherein primarily with respect to digital technology, a processor mayalso include primarily analog components. For example, some or all ofthe signal processing algorithms described herein may be implemented inanalog circuitry or mixed analog and digital circuitry. A computingenvironment can include any type of computer system, including, but notlimited to, a computer system based on a microprocessor, a mainframecomputer, a digital signal processor, a portable computing device, adevice controlling module, or a computational engine within anappliance, to name a few.

Conditional language such as, among others, “can,” “could,” “might” or“may,” unless specifically stated otherwise, are otherwise understoodwithin the context as used in general to convey that certain embodimentsinclude, while other embodiments do not include, certain features,elements and/or steps. Thus, such conditional language is not generallyintended to imply that features, elements and/or steps are in any wayrequired for one or more embodiments or that one or more embodimentsnecessarily include logic for deciding, with or without user input orprompting, whether these features, elements and/or steps are included orare to be performed in any particular embodiment.

Disjunctive language such as the phrase “at least one of X, Y, or Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to present that an item, term, etc., may beeither X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z).Thus, such disjunctive language is not generally intended to, and shouldnot, imply that certain embodiments require at least one of X, at leastone of Y, or at least one of Z to each be present.

Any process descriptions, elements or blocks in the flow views describedherein and/or depicted in the attached figures should be understood aspotentially representing modules, segments, or portions of code whichinclude one or more executable instructions for implementing specificlogical functions or elements in the process. Alternate implementationsare included within the scope of the embodiments described herein inwhich elements or functions may be deleted, executed out of order fromthat shown, or discussed, including substantially concurrently or inreverse order, depending on the functionality involved as would beunderstood by those skilled in the art.

Unless otherwise explicitly stated, articles such as “a” or “an” shouldgenerally be interpreted to include one or more described items.Accordingly, phrases such as “a device configured to” are intended toinclude one or more recited devices. Such one or more recited devicescan also be collectively configured to carry out the stated recitations.For example, “a processor configured to carry out recitations A, B andC” can include a first processor configured to carry out recitation Aworking in conjunction with a second processor configured to carry outrecitations B and C. The same holds true for the use of definitearticles used to introduce embodiment recitations. In addition, even ifa specific number of an introduced embodiment recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations).

It will be understood by those within the art that, in general, termsused herein, are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.).

For expository purposes, the term “horizontal” as used herein is definedas a plane parallel to the plane or surface of the floor of the area inwhich the system being described is used or the method being describedis performed, regardless of its orientation. The term “floor” can beinterchanged with the term “ground” or “water surface.” The term“vertical” refers to a direction perpendicular to the horizontal as justdefined. Terms such as “above,” “below,” “bottom,” “top,” “side,”“higher,” “lower,” “upper,” “over,” and “under,” are defined withrespect to the horizontal plane.

As used herein, the terms “attached,” “connected,” “mated,” and othersuch relational terms should be construed, unless otherwise noted, toinclude removable, moveable, fixed, adjustable, and/or releasableconnections or attachments. The connections/attachments can includedirect connections and/or connections having intermediate structurebetween the two components discussed.

Numbers preceded by a term such as “approximately,” “about,” and“substantially” as used herein include the recited numbers, and alsorepresent an amount close to the stated amount that still performs adesired function or achieves a desired result. For example, the terms“approximately,” “about,” and “substantially” may refer to an amountthat is within less than 10% of the stated amount. Features ofembodiments disclosed herein are preceded by a term such as“approximately,” “about,” and “substantially” as used herein representthe feature with some variability that still performs a desired functionor achieves a desired result for that feature.

It should be emphasized that many variations and modifications may bemade to the above-described embodiments, the elements of which are to beunderstood as being among other acceptable examples. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and protected by the following claims.

What is claimed is:
 1. An underwater detection apparatus, comprising: atransmission transducer configured to transmit a transmission wavewithin a given fan-shaped transmission space, the fan-shapedtransmission space having a first transmission width in a given firstplane and a second transmission width in a second plane perpendicular tothe first plane; a reception transducer configured to receive, as areception wave, a reflection wave of the transmission wave within agiven fan-shaped reception space, the fan-shaped reception space havinga first reception width in the first plane and a second reception widthin the second plane, the second reception width being wider than thesecond transmission width, and in the second plane, the fan-shapedtransmission space being within the fan-shaped reception space; and amotor configured to rotate the fan-shaped transmission space and thefan-shaped reception space.
 2. The underwater detection apparatus ofclaim 1, wherein: when the motor rotates in a given direction, thefan-shaped transmission space is positioned in a front half side of thefan-shaped reception space in the second plane relative to the givendirection.
 3. The underwater detection apparatus of claim 1, furthercomprising: a controller configured to control the motor, wherein thecontroller controls the motor to rotate at a given first speed whenperforming underwater detection with the transmission transducer and thereception transducer, and at a second speed faster than the first speedwhen not performing the underwater detection.
 4. The underwaterdetection apparatus of claim 3, wherein: the controller controls themotor to rotate in a given first direction when either performing or notperforming the underwater detection.
 5. The underwater detectionapparatus of claim 3, wherein: the controller controls the motor to:rotate in a given first direction when performing the underwaterdetection, and rotate in a given second direction, opposite of the firstdirection, when not performing the underwater detection.
 6. Theunderwater detection apparatus of claim 1, further comprising: adirection change mechanism configured to change a direction of thefan-shaped transmission space relative to the fan-shaped reception spacein the second plane, wherein when the motor changes a rotationdirection, the direction change mechanism changes a direction of thefan-shaped transmission space, a position of the fan-shaped transmissionspace in the second plane being shifted to a position in a back halfside of the fan-shaped reception space relative to the rotationdirection before the rotation direction is changed.
 7. The underwaterdetection apparatus of claim 2, further comprising: a second receptiontransducer configured to receive, as a reception wave, a reflection waveof the transmission wave within a given second fan-shaped receptionspace, the second fan-shaped reception space having a third receptionwidth in the first plane and a fourth reception width in the secondplane, the fourth reception width being wider than the secondtransmission width of the fan-shaped transmission space, and in thesecond plane, the fan-shaped transmission space being within the secondfan-shaped reception space, wherein: the motor is configured to rotatethe fan-shaped transmission space, the fan-shaped reception space andthe second fan-shaped reception space; and when the motor rotates in thegiven direction, the fan-shaped transmission space is positioned in aback half side of the second fan-shaped reception space in the secondplane relative to the given direction.
 8. The underwater detectionapparatus of claim 7, further comprising: a reception circuitry,connected to the reception transducer and to the second receptiontransducer, configured to generate a reception signal from the receptionwave received by the reception transducer and to generate a secondreception signal from the reception wave received by the secondreception transducer; and processing circuitry configured to generatedetection information based on the reception signal and the secondreception signal, wherein when the motor rotates in a given firstdirection, the processing circuitry generates the detection informationbased on the reception signal, and when the motor rotates in a seconddirection, different from the first direction, the processing circuitrygenerates the detection information based on the second receptionsignal.
 9. The underwater detection apparatus of claim 2, furthercomprising: a second transmission transducer configured to transmit asecond transmission wave within a given second fan-shaped transmissionspace, the second fan-shaped transmission space having a thirdtransmission width in the first plane and a fourth transmission width inthe second plane, wherein the second reception width of the fan-shapedreception space is wider than the fourth transmission width, and in thesecond plane, the second fan-shaped transmission space is within thefan-shaped reception space; the motor is configured to rotate thefan-shaped transmission space, the fan-shaped reception space and thesecond fan-shaped transmission space; and when the motor rotates in thegiven direction, the second fan-shaped transmission space is positionedin a back half side of the fan-shaped reception space in the secondplane relative to the given direction.
 10. The underwater detectionapparatus of claim 9, further comprising: processing circuitryconfigured to drive the transmission transducer and the secondtransmission transducer, wherein when the motor rotates in a given firstdirection, the processing circuitry drives the transmission transducer,and when the motor rotates in a second direction, different from thefirst direction, the processing circuitry drives the second transmissiontransducer.
 11. The underwater detection apparatus of claim 1, wherein:when the motor rotates in a given direction, one edge of a pair of edgesof the fan-shaped transmission space is positioned on a front edge ofthe fan-shaped reception space relative to the given direction.
 12. Theunderwater detection apparatus of claim 1, wherein: the fan-shapedtransmission space is a space in which a power of the transmission wavetransmitted by the transmission transducer is equal or higher than halfof a maximum power of the transmission wave; and the fan-shapedreception space is a space in which a reception power sensitivity of thereception transducer is equal or higher than half of a maximumsensitivity of the reception transducer.
 13. The underwater detectionapparatus of claim 1, wherein: the first plane is a vertical plane; andthe second plane is a horizontal plane.
 14. The underwater detectionapparatus of claim 1, wherein: the first plane is a plane including ahorizontal line; and the second plane is a vertical plane.
 15. Theunderwater detection apparatus of claim 1, wherein: the motor rotatesthe fan-shaped transmission space and the fan-shaped reception spaceabout an axis perpendicular to the second plane.
 16. The underwaterdetection apparatus of claim 1, wherein: the motor rotates thefan-shaped transmission space and the fan-shaped reception space byrotating the transmission transducer and the reception transducer. 17.The underwater detection apparatus of any of claim 1, wherein: thetransmission transducer and the reception transducer are differenttransducers.
 18. The underwater detection apparatus of claim 1, wherein:a transmission surface of the transmission transducer is making anoblique angle with a vertical plane; a reception surface of thereception transducer is making an oblique angle with a vertical plane;and a direction perpendicular to the transmission surface and adirection perpendicular to the reception surface are differentdirections.
 19. An underwater detection method, comprising: transmittinga transmission wave within a given fan-shaped transmission space, thefan-shaped transmission space having a first transmission width in agiven first plane and a second transmission width in a second planeperpendicular to the first plane; receiving, as a reception wave, areflection wave of the transmission wave within a given fan-shapedreception space, the fan-shaped reception space having a first receptionwidth in the first plane and a second reception width in the secondplane, the second reception width being wider than the secondtransmission width, and in the second plane, the fan-shaped transmissionspace being within the fan-shaped reception space; and rotating thefan-shaped transmission space and the fan-shaped reception space.